Firefox as of 51.0 and later now shows if you have 32-bit or 64-bit Firefox in About.

Windows users downloading from www.mozilla.org will get served a small online stub installer for 32-bit Firefox. So if you want 64-bit (Win64) Firefox then see www.mozilla.org/firefox/all/ and is also where you can get the full offline setups for Windows.

Actually as of Firefox 53.0, the 64-bit Windows 7 and later users can choose between the 32-bit or 64-bit in stub installer now. https://www.mozilla.org/firefox/53.0/releasenotes/

There's also this support article with other tips: How to switch from 32-bit to 64-bit Firefox

Does it matter if I use the 32-bit version on my 64-bit system? It seems to work ok.

I have another, unrelated question as well. In the security options general, I think I deleted mozilla allowed sites for add ons installation. Is that a problem?

I'm not very computer literate and I should never have messed around when I don't know what I am doing!

Hi susanjock, you wrote:

Does it matter if I use the 32-bit version on my 64-bit system? It seems to work ok.

That's the usual combination, so no problem.

In the security options general, I think I deleted mozilla allowed sites for add ons installation. Is that a problem?

You can always add new exceptions if you want to install an extension from a site (and you trust the site). Firefox will drop a little panel from the left end of the address bar with a button to allow it and then if you choose Allow, it will be added that Exceptions list.

Re: I think I deleted mozilla allowed sites for add ons installation.

This was Mozilla's own site, either under privacy or security options, that allows Mozilla to add on - probably should never have deleted it.

Deleting it shouldn't do any permanent harm. If you try to install a new extension do you get the option to re-allow it?

Thanks for all your help, jscher - I haven't tried to install any new extensions, so no clue if I will get an option to re-allow it. Since I am computer illiterate, the less stuff I do with the computer, the better off I am. But sometimes I poke around where I shouldn't, due to privacy and security fears. I guess as long as everything seems to be working ok, I should just leave it all alone.

I want to clarify my previous question. When I went into "options", then "exceptions", a box came up with "allowed sites Add-ons installation". Mozilla's own installation address was in that box and I deleted it - I should not have done that.

So, if Mozilla has add-ons it deems necessary, I may not get those add-ons. I am trying to figure out how to type that site back into the box, but I have no clue what it was - it was specific to Mozilla. I would like to know how to specifically enable the Mozilla browser to be able to install add ons that are necessary for say, security purposes, etc. I generally do not ever install my own add ons and use as few as possible.

I don't know if this is clear, but if anyone can help with this, I would really appreciate it.

Sure, I think it's unlikely that Mozilla will need to add an extension to your Firefox from the Add-ons site, but if you want to restore the entries for the Add-ons site, you can:

• Paste ftp://addons.mozilla.org and click Allow
• Paste https://addons.mozilla.org and click Allow
• Then click Save Changes

Thank you so much for your reply. Do I need to add and allow both of those?

Honestly, I don't know, but that's what I have listed.

Actually, mine also lists

http://addons.mozilla.org

but I think that is obsolete now, everything should be on one of the other two protocols.