If you recently updated Greasemonkey, you may need to launch a new window to get its button to show everything it normally does.

But more generally, could I suggest uninstalling Greasemonkey and installing the bizarrely named Violentmonkey instead? It is more backwards compatible with scripts developed before Firefox 57, and has a more mature user interface than Greasemonkey 4.x.

https://addons.mozilla.org/firefox/addon/violentmonkey/

Thank you, jscher2000. When you say "launch a new window" I take it you are referring to a new Firefox window. Where do I find the Greasemonkey 'button'. Are you saying I can use the 'button' to remove scripts?

It is scripts that I want to see. Should they be listed in about:addons?

I will have a look at Violentmonkey. I understand that the script has been updated for Firefox 57.

Yes, new Firefox window. Greasemonkey adds its button to the main toolbar. If you do not see it, and Greasemonkey is confirmed enabled on the Add-ons page, is it possible it has "overflowed" to the list displayed by the >> button?

I have looked at the Greasemonkey button. It doesn't allow me to see any existing user scripts, only the options "new user script" and "get user scripts" (as well as loading the GM home page or wiki).

My original question remains. Is there any way to find out what scripts are installed and any way to remove an existing script. The category is missing from the add-ons manager.

Greasemonkey 4 is not a very feature complete extension and I no longer use it on my main profile. I do have a test profile, and when I click the "monkey" button it shows the installed scripts and if I click a script, it has options to enable/disable, edit, and uninstall. Example screenshot attached. As far as I know, this is the only place to find the information.

Thanks. It seems to be then that any user script installed would be shown by clicking on the button.

I have now installed the related web extension instead.