If you want to make changes to many time entries at once, you can do that on any Time entries screen in your Productive account.
In the example below, we are editing time entries on budget level.
First things first, click on the checkbox on any individual time entry, to open up the multiple-select option.
As soon as you select any time entry, the blue toolbar will show up, in which you have three options to choose from: Billable time, Person, and Service and by clicking on each on them, you can apply changes to selected time entries.
Billable time - change the billable amount for many time entries at once
Person - move time entries to a different person on that project
Service - this will allow you to move all selected time entries to a different service on the same budget or different one of some other budget belonging to other project
There's also a fourth option, hidden under the "3 dots" on the right side of the footer. This will open up the delete functionality, which will allow you to delete all selected time entries.