Hi John,
I am Tanvi, and I would be happy to assist you today!
Firstly, Check Preferences:
1. Go to Edit > Preferences (or Photoshop > Preferences).
2. Select Workspace.
3. Ensure that Open Documents as Tabs is checked.
4. Also, make sure Allow Floating Document Windows is unchecked.
If the above doesn't work, try resetting your workspace.
Go to Window > Workspace > Reset <Workspace Name>.
If the problem persists, you can try creating a new preferences file.
Quit Photoshop. Then, Hold down Ctrl + Alt (or Cmd + Option on macOS) while starting Photoshop. A dialogue box asks if you want to delete the Photoshop preferences file. Choose Yes. Then Restart Photoshop.
Also, Ensure you have the latest version of Photoshop installed.
Updates often include bug fixes and performance improvements.
I hope this information helps. Please let me know if you have any other queries.
Good day