How do I add users to existing projects?

You can add existing users to a project or adjust their existing permission levels by following the steps below. 

Head over to Account Settings > Users 

Click on 'edit' for the user in question: 

Check the box next to the project(s) to which you wish to add the user, and adjust the permission level with the drop-down. Once you've made your selection, click Update User at the bottom of the list.