Hi, AmyV94551.
I can share some insights regarding changing thousands of job types in QuickBooks Desktop via the Import feature.
You can import the lists for the job type, however, this will not update the existing jobs on your QuickBooks Desktop. You'll need to open each customer's profile and update the job type from there.
You can go through the following write-ups below. It provides more information on what other lists you can import as well as the on what other formats that are supported in QuickBooks Desktop. Also, this will give you insights on what other ways to import and export:
Export, import, and edit IIF files
Import and export data in QuickBooks Desktop
You can always leave a reply below if you need additional assistance. I'll be around to help.