1. Can I migrate elements from a Firefox 47.0.1 profile on yosemite osx to the latest edition of Firefox (48) on el capitan osx ?

Are you avoiding updating to Firefox 48 on your Yosemite system? Doing that first would upconvert the files and potentially make them more compatible, but generally speaking, the changes between Firefox 47 and 48 are not huge.

2. the new "Customize (3 horizontal lines) button" on top right of menu bar. Where is the layout of this stored (I have modified mine to include the icons I wanted to), Preferably I wish to migrate this element of my Firefox Profile.

The prefs.js file stores many of your preference settings, plus the controls arranged on the main toolbar. It might also store the controls moved from there to other bars, but I don't do that, so I couldn't tell you for sure.

The xulstore.json file stores other toolbar layout information.

3. What is the best method to feedback, "suggestions to improve" any Firefox support KB article? I could not see any link on the KB articles I was reading.

You can use the "Edit Tools" in the left column of an article to start a discussion or mark up changes. It's a little complicated comparing across articles. For that you might use this forum: https://support.mozilla.org/forums/knowledge-base-articles

4. for the Items in KB1 not in KB3, is the Mozilla recommendation NOT to transfer these OR if desired, OK to transfer into new Fx Profile? I would like to transfer my toolbar customizations (Toolbar customization)

The articles are written with certain assumptions in mind. For example, you might set up Firefox Sync to share data between two different Firefox profiles, or you might just need one particular kind of data.

If you want to do a wholesale transplant of your old profile to the corresponding location on the new system, you can do that. See the next reply.

The trick with copying an old profile folder to the corresponding location on a new system is that Firefox won't notice it. Therefore, you can instead create a new profile, remove its contents, and replace its contents with the contents of an old profile folder. Here's how.

Overview

These are the steps described in more detail below:

1. Create a new Firefox profile (Firefox 47+)
2. Remove everything from that new profile folder
3. Copy in everything from the old profile folder

Before you start, have the old folder handy somewhere, for example, on an extenal hard drive, flash drive, or on the desktop.

Create a new Firefox profile (Mac)

In Firefox, type or paste about:profiles in the address bar and press Return to load that page.

Click the "Create New Profile" button and assign a name like OldSettings. Ignore the button for changing the folder location and click Finish.

Next, scroll down and below the Profile: OldSettings box, click the "Set as default profile" button.

Then scroll back to the top of the page and click the "Restart normally" button. This should quit Firefox and start Firefox up in that new profile.

Open the New Profile folder in Finder

Firefox in the new profile should look like a factory fresh installation. Open the Troubleshooting Information page using either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• Help menu > Troubleshooting Information
• type or paste about:support in the address bar and press Return

In the first table, click the "Show in Finder" button. Firefox will launch your brand new profile folder in Finder.

Leaving that folder open, switch back to Firefox, and Quit using either:

• "3-bar" menu button > "power" button
• (menu bar) Firefox > Quit

When Firefox closes, the Finder window showing the new profile folder should be front and center, or you can activate it.

Copy Old Data in Place of New

In that new profile folder, select all of the contents and delete it, so the folder is now empty.

Leaving that window open, open or switch over to your old profile folder. At this level you should see a folder named bookmarkbackups among other things. You want to make sure you're at that top level and not in a subfolder and not outside the folder.

Select everything and Copy.

Switch to the empty new profile folder in other window and Paste. This may take a minute since some of the files are large.

Start Firefox

Firefox should start up in that "new" profile with the resurrected old profile data. Success?

thankyou jscher2000. A very helpful reply.

by your replies -- it appears I missed highlighting an aspect. Apologises.

I am creating a brand new Fx Profile in OSX El Captain (brand new image on macbook) and wish to transfer components of my old Fx Profile. I do not wish to migrate the complete Fx profile at all/do not want to wholesale transplant my old profile.

answers to your questions. 1) Are you avoiding updating to Firefox 48 on your Yosemite system? No. No longer an option to upgrade F48 on Yosemite OSX.

2) I wont transfer prefs.js as Mozilla recommends not to. So I have screenshots of these settings. What would be great is if the toolbar and this custom button (3 horizontal lines) could be transferred as that is UI fiddly.

Is there a way to find out where the settings for Custom Button (3 horizontal lines icon is stored?

What does "other toolbar layout information" mean? Does it mean the toolbars but not the main toolbar?.

3. Thankyou

4. Sorry, I dont think my question was understood. In the KB on transfer it says if Mozilla recommends to transfer the component or not. In that KB there are 3 components missing (as listed above). My question is -- is it Mozilla recommendation NOT to transfer these?

5. new question: Where is the "tiles" configuration stored e.g. my current settings that I followed using this KB "Hide or display Tiles in New Tab". I have 9 tiles only showing and pinned 7 tiles and dont have anything else.

Thankyou for your help

jendrew said

What would be great is if the toolbar and this custom button (3 horizontal lines) could be transferred as that is UI fiddly.

Is there a way to find out where the settings for Custom Button (3 horizontal lines icon is stored?

The layout of buttons and controls on your toolbars and your application menu are conveniently stored in prefs.js under this preference (... is the actual data):

user_pref("browser.uiCustomization.state", "...");

You can transplant that data into your new prefs.js in place of the default value of that preference. There could be some discrepancies caused by differences in extensions, but Firefox should add anything that's missing.

What does "other toolbar layout information" mean? Does it mean the toolbars but not the main toolbar?

For example, which bars are displayed and which are not, the length of the address bar on the main toolbar, and the sizes of various windows and dialogs. Nothing earth shattering.

5. new question: Where is the "tiles" configuration stored e.g. my current settings that I followed using this KB "Hide or display Tiles in New Tab". I have 9 tiles only showing and pinned 7 tiles and dont have anything else.

Your pinned tile addresses are stored in prefs.js under this preference (... is the actual data):

user_pref("browser.newtabpage.pinned", "...");

The tiles you have X'd off the page might be stored in this preference, but the addresses are coded in a weird way that I don't understand, so... it could relate to entries in your old history rather than being a list of actual addresses.

user_pref("browser.newtabpage.blocked", "...");