When you make another player a leader, there is a confirmation pop-up. If you click "Yes" (intentionally or not), this is considered your personal decision.

If the leader does not appear in the game for a long time, or leaves the gang, their position is transferred to the captain who was the last to enter the game.
If there are no captains in the gang, or if the captains are also not active, the role of the leader is given to the member who entered the game most recently.

Please note that we do not return gang leader rights that have been lost by mistake or due to inactivity.We don't think it's fair for the developers to interfere with our players' in-game lives.
Unfortunately, we cannot make another player the leader; you can either ask that player to return the leadership to you, or wait for the leadership to change automatically when they become inactive.