You can change clients/projects after the time entry is saved by reassigning the entry.
To do this:
Select the entry
Click 'Assign' in the top header
Search for the correct client/project
Save
You can also do this via your Recent Projects list:
Reassigning Time from a Temporary Matter Across Multiple Days
If you’ve assigned time to a temporary matter and need to reassign it to the correct matter across multiple days, follow these steps:
Click the three-dot menu on the temporary matter entry and select Bulk Actions to open the Time Control page.
Search for the temporary matter using the search bar to locate the relevant entries.
Select all entries by checking the box next to Date at the top of the list.
Click Assign, search for the correct matter, and click Save to finalize the reassignment.