If you think that the issue is caused by an addon, please try running Firefox in safe mode. 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.

The NoScript extension adds a button to the toolbar. Hover over that button and a list drops down showing what is blocked in the page (shows "Allow" or "Temporarily allow" next to it) and what is allowed (shows "Forbid" next to it). You can use "Temporarily allow" for various servers as a test to see whether that gets the page working.

Note: If you don't have a lot of patience to use that menu, then NoScript is not a good fit for you. It requires a lot of "training" to know which sites you trust.

Note that some sites may intercept the paste command. YouTube and Facebook are other examples of this. If you have changed any settings related to pasting, that may cause issues on other sites.

Thank you for the feedback. Unfortunately, none of the suggestions helped. Here is what I did. First I uninstalled Firefox and all folders scattered throughout the various hiding places for settings and other information about Firefox, including Mozilla Maintenance Service. I reinstalled Firefox. I did not install NoScript. There are only a few extensions and plug-ins. I still could not copy and paste on the Outlook website. I even tried starting Firefox in safe mode, which made no difference. What's funny is that RoboForm successfully fills the login information and signs me in. I can login if I type the information, but it doesn't matter where I copy the login information from, I cannot paste it into the fields on the Outlook website. I can with IE 11 and Edge. So the next thing I tried was to disable hardware acceleration, and every extension and add-on. That did not work either. Next, I ran, in safe mode, the following programs: Malwarbytes Premium, SUPERAntiSpyware Professional, Microsoft Safety Scanner , Anti-Rootkit Utility - TDSSKiller , AdwCleaner and McAfee AntiVirus Plus. None of the programs found anything wrong. I have two password managers, RoboForm and a free one called KeePass. There are some websites where RoboForm won't work and I have to use KeePass. I don't know how long I've had this problem with Outlook. Usually, I just use RoboForm because it is easier. I really don't know what else I can try. It is definitely something to do with Firefox. If anyone else has any suggestions, I'm all ears.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. Is the problem still there?

RightToClick {web link} Stops javascript annoyances such as forbidden right click, forbidden text selection or cascading dialog boxes.

You can try alternatives like Shift+Insert to paste.

Use keyboard shortcuts if the buttons on the web page or other methods aren't working.

• Copy: Ctrl+C or Ctrl+Insert (Mac: Command + C)
• Paste: Ctrl+V or Shift+Insert (Mac: Command + V)
• Cut: Ctrl+X or Shift+Delete (Mac: Command + X)

cor-el,

Thanks for the tip. I am able to use a combination of KeePass and Ctrl+V to enter my login information. KeePass has two icons at the top of the application window. One is for the username and the other for your password. Usually, you left click on the icons, then right click in the appropriate box and choose paste. Now, I left click on the icons, which copies the information to the clipboard, then left click in the appropriate box and use Ctrl+V to paste. It is a fairly easy work around. Of course, I wish KeePass worked like it usually does. Actually, it is not just KeePass, it doesn't matter where I copy the information from, I cannot paste it using the mouse or touchpad. Thanks again!