@DonNelson Gotcha! Looks like you're using the SIS import functionality. The USER_ID column is the SIS ID when looking at a user's account in the Canvas interface.

First, you need to check in the People page (not the file!) if the student has a 2nd Canvas account with the incorrect SIS ID. There is a good chance that this has happened, if the first file sent the wrong USER_ID/SIS ID (this value must be unique per Canvas account.)

If this is the case and the student has two accounts, you'll want to merge the two accounts, and make sure that on the resulting merge that the student has the correct SIS ID. 

If the student truly has one account and the right SIS ID is not being applied, just run a change_sis_id.csv file to change the student's SIS ID OR you can change it in the interface by editing the user.

I would highly advise that you do this in BETA first to see if there's any issues/side-effects before doing this on the live accounts.