Timesheets.com has tools (that are currently unreleased to the public) that allow us to update bill and cost rates for many users at once. This includes the default bill and cost rates shown on the Project and Account Codes lists, but also includes override rates on an individual basis.
Once we’re able to make these tools available to the general public, we’ll do so. In the meantime, if you need assistance updating many bill or cost rates, please contact us.