When i use zero gravity and its my opponents turn can they swich thier monsers back during the same turn? and the same quetionn goes for if its my turn can i swich my monsters back to atk or def?

thanks

As long as you/your opponent, haven't done 1 of the following then yes they/you can change the position back:

1. Summoned the monster(s) that turn.

2. Manually changed the monster(s) that turn.

3. Attacked with the monster(s) that turn.