By going back and forth with a restore has possible mucked that up and if was at all possible to figure out history for clicked links.

As to why that happened, no idea. Maybe the site was doing some work or testing. I know a few forums that do not change colour for links you have visited.

Shows here you have version 61.0 if that is so you are a update behind. Please go to Help --> About. It will show your version number and or update you and there is a link there that say's What's New. This will show what has been fixed and improvements as well as security.

Did you use a cookie cleaner or any type of program like that or run in Private Browsing or have the Check Box ticked for Tracking Protection Always as that would stop that also.

Suggest keep track and if it is something that is a must for you then maybe a clean reinstall (but ask us as we do a clean install differently than you would ). Myself no idea, no information was provided when you asked the question regarding your system so no idea if a adblocker blocked a cookie that you wanted to keep or even your security software.

I am on FF 61.0.1.

I didn't do the restore until after I noticed the problem. When that made no difference I un-did it and went back to the current state.

The 2 sites I looked at changed colors because I used the CCS function to use custom colors,

Even if the sites didn't use colors, all the threads should not appears as if I read all of them. It's as if I had clicked on "Read All" button and wiped out all the new Bold font entries. I looked at another forum today which does not use colors and all the threads indicate they have been read except for new entries since yesterday.

Did not use a cookie cleaner or anything like that.

I don't need to do a re-install because everything is working now, except for the fact all my old visited links data is missing.

Yesterday, when I went to the 2nd forum to check it out, it initially showed visited links colors. But after I looked at a thread all the colors disappeared. So the data was there but then "poof" it was gone.

Is this a site other can see to see what happens if they go there? Also if there is nothing loaded just FF default what happens?

Hi, also since no information was supplied regarding your system info and Firefox Extensions when you made the question please : Try Firefox Safe Mode to TEST & see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

Firefox will color links based on your history. So if a link is no longer in your history, or if the one in history does not match exactly, then the link will show as unvisited. It's hard to explain how links you didn't visit could show as visited, however.

Websites may independently style links as visited or unvisited, or as having new content. Often forums accumulate and apply this data when you are logged into the site. This approach is not based on Firefox history, it is based on data managed by the site itself.

Mike109 said

The 2 sites I looked at changed colors because I used the CCS function to use custom colors,

Could you describe what you've customized in more detail? Can you test with the customizations disabled -- the Firefox Safe Mode test mentioned in an earlier reply could help with that.

Try to clear the Cache and remove the Cookies from websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" from websites that cause problems:

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Manage Data

"Clear the Cache":

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear