You can easily test this. The settings are not being saved to everyone. This is an issue that was raised over a month ago and in some point it was said that it is fixed but it turned out that is wasn’t fixed.
The post that explains this issue (https://community.thunkable.com/t/admob-settings-not-saving/1537457) is deleted or merged with another post and cannot be found. You can see this post instead [Solved] Can't assign Camera and AdMob settings. Although this post says [Solved], it is actually NOT YET SOLVED.
Open any project, go to projects settings and type anything in AdMod App ID for both Android and iOS. Exit the project and open it again and check these settings again and you will see them empty.
iOS needs to track the apps and when this setting is not provided it will give the Signal 6 error.
That is the whole story.
Currently and until this is fixed, you have to remember to key in these values every time you want to publish the app.
I hope this clarifies the situation.