Dual Monitor use issue

Do you have more than one display connected? Are they working?

The Arrangement tab is supposed to appear ONLY when there is more than one display.

Furthermore, in that case, it will show only in the "main" display.

Below are the two windows for System Preferences->Displays that I see in my mac with two displays working as extended desktop (10.15.3). Note that only one of them has an arrangement tab.

Can you tell us what problem you are experiencing?

Is a display not being recognized? How is it connected?

What do you see in System Preferences->Displays?

Normally, a display should be recognized immediately.

By holding down the Option key, a button "Detect Displays" appears, but in my experience if the display is not detected automatically it is unlikely that pressing this button will make it appear.

Maybe I misunderstood the question... if you see the same image in both displays, but you want them to work as an extended desktop instead, there are two ways to do it: either uncheck a box in System Preferences->Displays->Arrangement, or, much easier, just press Command-F1