This problem seems to have been corrected with 1.37.9.0 - released to beta flyers this afternoon. If the final release of SU15 is released Tuesday, as scheduled, it should be corrected for all.
2 Likes
Iāve had it since it first started happening. Updated to 1.37.9.0 last evening and it appears to be resolved (on my system at least).
1 Like
I concur. Solved in the last beta update.
Same for me today, not flown for a week and wasnāt doing it before. Load in and it goes to windowed mode automatically after checking for updates. Not on BETA but on DX12.
This has been happening for me for at least two weeks now, also NOT in the beta. Everytime I startup the sim, Iām in window mode and have to reset to full screen.
I have been getting this issue lately. Minor inconvenience. I just alt enter.
I have this too and I am not in the beta. For some reason my msfs now starts in windowed mode every time I start it.
This only started happening about a week ago
Same here.
Iāve got the same problem 
without solution
Hi @Speedbrake22, @hueyfoe, and @IslandWing
As stated in the title of the thread, this issue has been resolved in version 1.37.9.0, which is currently the active SU15 beta build. When SU15 releases in April, this issue will be resolved for all players. If you do not wish to join the SU15 beta, you can work around this bug by simply pressing ALT + ENTER on your keyboard when you reach the main menu to return to fullscreen mode.
Thanks,
The MSFS Team
2 Likes
Same problem here.
Hello,
I have the same issue with starting the game. The version is 1.36.2.0 and while it starts in full screen, as soon as the installation manager screen appears, it checks so quick and without any update the screen goes to windows mode. I can not update the game manually even from the steram website. Microsoft store does not show my installed game app. What do I need to do in order to update this game manually? It does not update anything whilew most of you say that the game version is 1.37.9.0 now ! Please help me as the game install folder is already more than 500 gb and installing it again will take about 2 days with the slow speed of microsoft servers.
The full release version of the game is NOT 1.37.9.0 - that is the current beta/test build that some are using.
The windowing of the game has been rectified in the current 1.37.9.0 test build, which has been mentioned in this thread several times. It is due for release sometime in April I believe.
1 Like
I can see why you are getting confused. This āfalse updateā you think you are missing out on is not going update you to 1.37.9.0 as there is no actual update!
To actually get an update (and so solve the problem) you need to join the beta program and then you will get 1.37.9.0. However given that everyone should be updated to this version soon and if youāre not comfortable joining the beta you may wish to wait.
Do you have the same issue if you follow the OPās steps to reproduce it?
Bug is consistentā¦ FS will normally drop out of Fullscreen and into Windowed after going to World menu and selecting a departure and arrival location and then flying.
Provide extra information to complete the original description of the issue:
FS is in Fullscreen and then drops to windowed on its own.
Are you using DX11 or DX12?
DX11
Are you using DLSS?
Yes
If relevant, provide additional screenshots/video:
This problem just started happening for me. I set FS to Fullscreen, save it, etc. and all seems good, but then most of the time if I go to World menu and select a departure and arrival point and then fly, FS will drop Fullscreen and revert to Windowed mode.
Do you have the same issue if you follow the OPās steps to reproduce it?
Yes
Provide extra information to complete the original description of the issue:
n/a
Are you using DX11 or DX12?
DX11
Are you using DLSS?
Yes
If relevant, provide additional screenshots/video:
This is a good example of incredibly poor software QA. This is an obvious error which should have been spotted and fixed before software release.
3 Likes
Iām looking forward to the next SU, hope itās fixed 
Happening to me as well.