How to update a field for n rows in quickbase

This sounds like something you would use grid edit for

1. Order the rows so that the records you need to update are in the same order

2. select grid edit from the menu next to the New button or above the table if this is a sub report

3. Double click the first item and edit its value

4. select the other rows you need to make the same value

5. Right click and select fill down

6. save the changes