Unable to give slide control to other participant in Ver. 6.0

Hi, I'm having a litte trouble in zoom meeting. Since I start using version 6.0, I cant't give slide cotnrol to other participants. I checked the setting of the account, and is allowed.  I can see the list of participants to give slide contorol to in my PC (the one sharing PPT), but the arrow to move slide doesn't show in PC (the one I give slide contorol to). Does anyone now the solution to this probleｍ？