There’s actually a similar problem posted few weeks ago.
This is the thread if you want to take a peek.
But to summarize it, the change happened inside the stats page will only take place when you progress on the main story (which is done by either pressing NEXT button or making a choice on the story)
That being said, you can go stats screen > main game > stats screen > main game over and over again, but only the changes occured on the most latest “> stats screen” will take place.
As for a note, tablet user can play CoG/HG games with both main story and the stats screen page active at the same time. Perhaps, this helps you to imagine how altering stats on the stats screen works.
P.S. It’s night at here 