[A} Unfortunately, permissions of a single user of a particular team cannot be altered.
[B] To change the permission of a single user, that user should no longer be a part of that team.
[C] Then create a new team with that user as the only member. By changing the permissions of this newly created team, you can change permissions for that user.
[D] Go to the Settings module and select the Users tab. Click on Add Team.
[E] Fill in the team name and description and click Save Details.
[F] After the new team is created, go to the user whose permission is to be changed. Click on the edit icon next to their name.
[G] In the Team field, change their team to the one that you just created. Click on Save Details
[H] Under the Teams tab, go to the recently created team.
[I] Go to Permissions(1) and select all the permissions you wish to give. Click on Save(2). Now the permissions of this particular user have been changed.