To revert to default link colors, use the Reset Firefox option, but good luck finding it because they are so prone to moving and relocating features (like the Take Screenshot option that was already moved twice).

I use the colors; Red = Unvisited link Green - visited link.

Just set the colors to whatever you want.

Also see; https://addons.mozilla.org/en-US/firefox/addon/nosquint-plus/ NoSquint Plus by Baris Derin

Manage site-specific zoom levels and color settings

What are your current color settings ? Do you override the website colors (Override the colors specified by the page with your selections above) ? Note that always overriding website colors also disables background images.

Thanks for the quick responses,

@cor-el Currently the Override is set to 'Never'. Despite this, it still overrides. Could there be other settings affecting this? Perhaps an issue with syncing across multiple devices?

Are you using Sync ?

You can create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Yes, I am using sync across multiple devices, including a desktop, a laptop and a mobile device. Will this change how transferring files to a new profile will function?