The changes stay there for a few days and then, after a few clicks in the continue, they go and usually revert to some sort of default position.
I know this by doing a simple test. I add every goalkeeper from my squad, b team, under 23s and under 19s. About 10 goalkeepers in total. A few days later I am back to 3. There is no quitting a d reloading the game at any point.