Hi, you should be able to right click > Delete.

If that isn't working, try Firefox Safe Mode to 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. Thank you!

You can type a common character like a colon (:) in the search bar in the History Manager and sort the list by visit date.

I restarted in Safe Mode, but it appeared to make no difference.

Open Menu -> History opens a short list of history items, but left click opens the page, and right click has no effect.

Open Menu -> History -> Show All History opens all history, with dates Today, Yesterday, Last 7 days, etc., but does not show visits in the future.

I don't know the date of the visits, as I changed the date accidentally, then corrected it - if I knew the date of the visit, I could reset the date on the computer, and delete "today" or whatever, but I don't know the date.

Did you try to use the search bar in the Library as I suggested above to bypass the filtering that is applied to the default folders?

I typed the : as suggested, then order by date, but it didn't help.

I assumed from your suggestion that you meant, just do that, and the sites will appear at the top (or bottom) of the list, but that didn't happen.

HOWEVER, after trying that again, I could type the text that appears in the history into the search bar. I could see the pages, and deleted them successfully.

However, it moved me in the right direction, and resolved the issue.

Thank you for your help.