I just finished a game where I promoted a pawn and it automatically assumes that you want a queen when you promote. In this particular instance it would have been more handy for me to promote to a knight. You can promote to any piece you wish OTB, so I think you should have the option in L'il Chess Partner, too.
This is a serious enough issue, though, that you should go back to the programmer and ask them to change it or use a different program. There could well be a position where promoting to a queen could result in stalemate where promoting to some other piece results in a win. Someone not familiar with the program may well promote the pawn thinking they can get any piece they want and have their game ruined by having a queen forced on them.
I just finished a game where I promoted a pawn and it automatically assumes that you want a queen when you promote. In this particular instance it would have been more handy for me to promote to a knight. You can promote to any piece you wish OTB, so I think you should have the option in L'il Chess Partner, too.