I don't know what arrangement you're using, but it sounds like you should save your desktop layouts?
Panels are placed in whatever location they were used in last, which may be an entirely new side window/bar if it's not open/in use already. This sounds like your issue.
Note that Inspector is not the same. There is SCH Inspector and PCB Inspector, and similarly for List, Query, etc. Compiler and Messages I think are common, along with the other system ones (Storage, etc.). You need to adjust both versions to your preferred positions and sizes.
Then save to a desktop layout and link it on the menu for quick access.
It WILL forget the layout when you move around the main window, or change monitors or desktop size, etc. I think they remember their monitor number, or absolute desktop position, something like that.
Then do it all over again say for a single-screen setup. I'm fond of docking all the panels as one sidebar, pinned or collapsed as the case may be. It's a little less efficient, but when I'm mobile, productivity isn't my number one priority. So, something handy like that is good when you're working on a docked laptop, getting up sometimes for meetings/presentations. With the two desktop configurations, I can swap between both just fine.
The one thing you can't save, is the position of dialogs. These are used a bit less since AD18, but it depends if you prefer panels or dialogs for editing things. Some people use panels as dialogs, for that matter (like the InspectorProperties panel replacing the double-click dialog)...
Tim