Unable to modify user and roles

[Pavithra Bathrachalam]

We are trying to update the access for our developers on the 'Users and Roles', but we don't seem to be able to add more than one role to some individuals.
We would like to change all developers access on this list to have 'developer' and 'user' access but can't seem to update this. 

Attaching screenshot for your reference

[Mohanraj Thangamuthu]

Hello, Good day. We don't have screenshot attached yet. For few users you are able to add two different roles on same project ?