Why does exiting out of Fullscreen app rearrange all my desktops?

I have the same problem in mac os sonoma and in previous versions as well. The turning off of the 'rearrange spaces....' has been turned off on my computers for years and still I find that Apple rearranges my apps at will. I think it has a fundamental problem with no specific apps assigned to desktop 1. I leave this desktop with no assigned apps so it will be empty for whatever app I choose to work on at the moment and have been doing this since OS 10.0 many years ago. I keep my browser open in desktop 2 and my email app in desktop 3 and all are appropriately assigned to those desktops. Even so, at least once a week I will try to go to desktop 1 only to find it doesn't work because I am already in desktop 1, with my browser, which Apple has decided to put there for some reason of it own. I have searched online over the years and have yet to find a solution to this problem, other than to not use alternate desktops so Apple can't move things around.

There is a setting in Mission Control to rearrange spaces based on usage. Sounds like you want that off.

William Dalzell wrote:

I have the same problem in mac os sonoma and in previous versions as well. The turning off of the 'rearrange spaces....' has been turned off on my computers for years and still I find that Apple rearranges my apps at will. I think it has a fundamental problem with no specific apps assigned to desktop 1. I leave this desktop with no assigned apps so it will be empty for whatever app I choose to work on at the moment and have been doing this since OS 10.0 many years ago. I keep my browser open in desktop 2 and my email app in desktop 3 and all are appropriately assigned to those desktops. Even so, at least once a week I will try to go to desktop 1 only to find it doesn't work because I am already in desktop 1, with my browser, which Apple has decided to put there for some reason of it own. I have searched online over the years and have yet to find a solution to this problem, other than to not use alternate desktops so Apple can't move things around.

Sorry, no idea. I don't use it enough to pay attention. Note that what you may think is the App is really a "document" window. Those can be put anywhere you choose and are not "assigned" to any space.

If you have an app assigned to Desktop 3, but you are on Desktop 1 when you open a new window in the app, I don't know what it will do. There is a setting that says to switch to a Desktop with Open window when switching to an app. I don't know how that will affect your setup.

I also have switch to an open window turned off. I've been fighting this problem for years and when it moves my browser to desktop 1 it isn't because of opening a document. This isn't a 'document window' problem, it is a problem of an app, most often the browser app, being moved from its assigned desktop to desktop 1, which should be impossible to do on its own.