Assign a role
The project owner either assigns a role when it is created by selecting "Assign this role to collaborators or groups" (see "Create a project role") or on a per-collaborator basis later on.
To assign a role to a collaborator, go to the "Collaborators" window and click on the collaborator you want to assign a role to.
Go to "Permissions" in the top menu of the collaborator's card
Select the role you want to assign your collaborator from the dropdown menu. The permissions will automatically be updated to the permissions granted to this role. If the collaborator already has an assigned role, you can change it here.
Click "Update"
Remove a role
Go to the "Collaborators" window and click the collaborator you want to remove from the role.
Go to "Permissions"
Click on the "x" next to the selected role
The permissions assigned to the role will still be active, but they can be changed now.
Click "Update" to save your changes