Bill Rate Locking
Project Bill Rate Locking
Bill rates are locked by default on billable, time & materials projects. This setting will ensure that any bill rate changes to work roles or members will not be reflected on time logged against this project. If you want a project to receive any bill rate changes that may occur, then simply turn off the rate locker.
Work Item Bill Rate Locking
Work items that are created inside a project will automatically inherit the bill rate locking status of the project. However, you can modify this by changing the bill rate source to either "Work Role" or "Member".