The Options dialog is too large?

If you uninstalled and removed all personal data (this nukes your bookmarks, so hopefully you didn't do that or you had a backup), then the usual culprit -- a corrupted settings file -- should have been cleared.

If you need to clear it manually, here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either:

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

In the first table on the page, click the "Show Folder" button to launch a new Windows Explorer window showing your settings files.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• File menu > Exit

Pause while Firefox finishes its cleanup, then rename localstore.rdf to something like localstore.old

Start Firefox up again. Is the dialog back to normal?

As a temporary workaround, you can use an "under construction" feature, which is the Options dialog converted to a tab. In the address bar of a new tab, type or paste about:preferences and press Enter to load it. (For me, it takes several seconds to display.)

the box in general is to big. Which makes zero sense. On my old computer I had the DPI settings on windows set rather high, and I'm using the same DPI now...firefox window did not blow up on that one.

uploaded a file if that helps

I looked, no localstore.old

and I've tried the options in tab instead, the settings won't all save for me when I want them to.

Was your old computer running Windows XP? There is a difference in how Firefox handles high DPI on Windows 7 compared with XP. It sounds like you know about the option to decouple Firefox from the Windows DPI setting but you don't want to use it.

Could you check whether Firefox is running with any backwards compatibility settings? Right-click the Firefox icon > Properties > Compatibility. Make sure nothing is selected on that tab.

my old computer was windows 7, and I had no problem putting the DPI at high level and Firefox. scrolling is a bit weird on some sites because of it, but nothing like this at all.

and nope no box checked

my old one ran windows 7 home. this ones windows 7 professional . IDK if that makes any difference. I think it does, I'm having a bit of difficulty getting things set up to my liking.

What DPI setting do you use in Windows and what is the value of the layout.css.devPixelsPerPx pref on the about:config page?

You can look at this extension to adjust the font size for the user interface.

• Theme Font & Size Changer: https://addons.mozilla.org/firefox/addon/theme-font-size-changer/

You can look at the Default FullZoom Level or NoScript extension if web pages need to be adjusted after changing layout.css.devPixelsPerPx.

• Default FullZoom Level: https://addons.mozilla.org/firefox/addon/default-fullzoom-level/
• NoSquint: https://addons.mozilla.org/firefox/addon/nosquint/