Thanks for the suggestion, we agree and are aiming to improve this in an upcoming patch.
@hock132 This would be nice if it showed up in the pre-game menu.
However there is another way to get this to work. Go to Fanhub -> Team Manager -> List Manager, and change the order of the list around to how you want it.
This will change your starting lineup for all games, including online.
Thanks @SaintSkeeta that's correct.
You can also edit the default lineups through Single Match->Team Management and using the "save to default" button.