To enable inline editing on the report run page, select Enable Field Editing.
When you apply an edit to a cell, the background color changes to indicate that a new value is stored locally. Change one or more values, and then save your changes.
Considerations
You can edit a maximum of 100 values at one time across multiple rows and columns.
In each row, you can edit a maximum of 12 report columns at one time.
There can be additional restrictions on inline editing of multiple fields based on the underlying Salesforce objects, custom settings, and dependencies among the fields you’re modifying.
Lookup filters aren’t applied to picklist field values. Be sure to select values that are valid for the record that you’re editing.
If you edit a cell that has related cells and the report requires a refresh to obtain up-to-date values, the related cells are marked Pending. When you save your changes, the cells update with the new values.