You can check this article.

• https://support.mozilla.org/en-US/kb/extensions-button

You can also check the Browser Console (not the Web Console) for messages about this extension.

• https://firefox-source-docs.mozilla.org/devtools-user/browser_console/

What goes wrong when you try to use it?

I tested on a simple page and it inserted its toolbar and let me tweak something and preview. But I don't use it often enough to notice changes.

The author has an email support link in the left column of the add-on page if needed: https://addons.mozilla.org/firefox/addon/print-edit-we/

Thanks for the replies. I contacted the developer who had me uninstall and reinstall. Works now. Once again, it's the simplest solution....