Remote Desktop Only Uses One Monitor

Do this first

1. Find the Remote Desktop shortcut you use to connect. It ends in .rdp and is usually on your desktop.
2. Right-click it. On Windows 11 you may need to click Show more options first.
3. Choose Edit.
4. Click the Display tab.
5. Tick the box marked Use all my monitors for the remote session.
6. Go back to the General tab and click Save.
7. Connect again.

Why it has to be saved. The setting lives inside that shortcut file rather than in Remote Desktop itself. If you change it from the Remote Desktop window without saving back to the file, it works this once and then forgets. Editing the shortcut and saving makes it stick for good.

If you do not have a shortcut file

If you start Remote Desktop from the Start menu and type the server name each time:

1. Open Remote Desktop Connection.
2. Click Show Options at the bottom left.
3. Click the Display tab and tick Use all my monitors for the remote session.
4. Go back to the General tab, type the server name, and click Save As.
5. Save it to your desktop. From now on, open it from there and the setting comes with it.

A couple of things worth knowing

Your monitors need to be arranged as one continuous row in Windows display settings for this to work smoothly. If one screen sits off on its own, the remote session can leave gaps.

If you only want two of your three screens used, that is not something Remote Desktop offers directly. It is all of them or one of them.