Here's a preview of the spreadsheet I'm editing in Google Drive:
The transaction type cell has a value of "debit" if the row is for an expense, and "credit" if it is income.
I would like a script to go through each row, and add a minus sign before the value in the "amount" column, if the value in the "transaction Type" column has a value of "debit".
Best Answer
Maybe give this a try:
Add above script to the script editor and run
onOpen()
by clicking the 'play' button. Then go back to the sheet, where you should see a newly created menu-item 'Custom Menu'. From there click on 'Make negative' and see if this works.