Every time I start it, the settings change and it goes into windowed mode.

I solved with this way:

1. go to your local app settings, mine here: C:\Users\USER\AppData\Local\EA SPORTS FC 26\fcsetup.ini (or something with setup)

2. open the file, make sure the settings is correct, in this case i want to force it always in fullscreen, so i make sure the fullscreen is true/1

3. right click on the file, and check the read-only

I recently changed to AMD. Did you end up finding a fix?

I play one two pcs one has amd the other nvidia both launch in windowed mode every time. Also if I have custom graphics settings such as all ultra and ray traced ambient occlusions. It defaults my graphics settings to ultra. Whatever render setting you have your custom set to, all other setting will be the same.

I have the exact same issue, and I have and AMD GPU

I have a question.  In fc26 companion app.  When i press my back button at bottom of screen it minimises the app.   It used to go back to previous page on the companion app and then back again would go back further in app.  Just shuts the app  

Can confirm this issue. Every time it launches in the windowed mode. The Nvidia App settings are working correctly and they don't mess this thing up. Sounds like EA isssueeee, hello boys. Time to work!

I have same issue where it always launches windowed. I know it is due to the Nvidia control panel since i made a change to my framerate there and ever since this issue is occurring. The problem is that I have restored to defaults and it still does this. if someone has a more detailed solution instead of "go to graphics elements and change it there", I would appreciate it. I have also told Nvidia control panel to launch in fullscreen and still no dice.

I have a same problem and also use nvidia gpu. in nvidia app is Full screen but it still launch in window mode.

If ur using a nvigia gpu, go to the nvidia app>graphics elements and change it there, figured it out that this keeps overriding eas config

i have the same problem with the resolution, but still cant figure how to fix it.