Only the group leader and seniors are able to increase the level for the group activities. You have to level all of the before you can increase one group activity. For example: If your group rank and study skills is at level 7, while your lucky wheel and group activity is at level 6, you must level both lucky wheel and group activity to level 7 and group rank to 8, so you can be able to level any of the other three choices to level 8. The more your group donates, the faster upgrades come.