screen format, have lost the yellow reduce button

Exit Full Screen using Esc, the menu command, or the green dot.

The yellow dot has never exited Full Screen.

I also don’t use Firefox, so I don’t know how you tell it not to open Full Screen. I would assume quitting it while not in Full Screen might do it.

larryklein2001 wrote:

I'll explain once again: Firefox opens in Full Screen Mode, which I don't like, but can not figure out how to stop.

As I wrote the answer is likely to be found in Firefox's settings. You can reset them to defaults by using Refresh Firefox: https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings, but if that does not work then you ought to consult a Firefox expert or participate in a Firefox user to user support forum.

larryklein2001 wrote:

Telling me I'm in full screen mode does not help. Looking for two opposing arrows in upper right corner does not help, because there are no such arrows. I can click on Exit Full Screen in View, but then I lose the toolbar at the top.

I guess you missed the part where I told you can’t minimize full screen windows. Or, do you not understand that the yellow dot is the minimize button. Being that it has no function while in Full Screen, it is disabled.

I have no idea what “two opposing arrows” has to do your question or my answer.

You appear to be in Full Screen. You can't minimize Full Screen windows. There really isn't a point. They exist in their own world and minimizing would just make it go away. A full screen Desktop doesn't exist unless there is a window to display.

... I can click on Exit Full Screen in View, but then I lose the toolbar at the top.

That's a separate problem. Investigate Firefox's settings regarding its Toolbar.

There is a system setting, I think it’s in Dock, to minimize documents to the app or not.

If you search the system settings for minimize, it will probably pull up.

I have no idea how that is possible. Can you post a screenshot?