When you make a rate change it only applies to slips created after the change. When you save it you get a wizard to apply the change to already entered unbilled slips. You have to specify criteria for what should be updated. It sounds like your criteria missed some. It’s really hard to say without knowing what you selected. You do have ability to export fields from one slip to others. Make a backup first because if you choose wrong criteria and change the wrong things you can’t undo  

Thanks for the response.  The change was made to the client and the billing clerk said she told the wizard to make it effective 9/1/2019--is there any chance that this update could be affected by the source of the original slip--whether it was entered directly into Timeslips or whether the slip came in through the e-center?  The baffling part was the fact that 2 slips, same TK, same client, same date and one was updated but the other was not (the TK did not remember whether he entered these in the e-center or not).  And, the most problems with updating are reflected in one timekeeper who enters all of her slips via e-center.