It's nice to have you back here, tah-difinitigrou.

I can see how important for you to be able to revise employee's historical cost rates for projects in QuickBooks Online. For now, the option to do so is by opening each timesheet and from there you can edit the rate. Please note that we want you to save time and keep things simple when doing a task in Quickbooks. 

Here's how:

1. Click the Reports tab.
2. In the search field, enter Time Activities by Employee Detail.
3. Click on the Activity Date or Customer name.
4. From the Time Activity page, modify the Cost rate (/hr).
5. Click Save and close.

I would also encourage you to visit our QuickBooks Online blog regularly. From there, you'll be updated with the features and enhancements that our developers are currently working on.

Please let me know if you need anything else. I'm always here to help.