File status updates automatically.  So if I change a file and then switch back to Sourcetree the file status section updates.  However, if I pull commits from the repository or make a commit locally the branch history auto-update doesn't happen.  Also, with "Current branch" selected, if I switch branches outside of Sourcetree the branch history auto-update doesn't execute.  The only way to get branch history to update in these scenarios is to switch from "Current branch" to "All branches" or vice versa.