I am trying to change my fingerprint as it is not reading mine. I also want to add my husband's.

This is the High Sierra forum, Touch ID is not available on Macs running High Sierra.

If you have a compatible Mac (M1 models) running macOS 11 Big Sur or later, then go to System Preferences->Touch ID and Click on Add Finger Print to add an additional fingerprint for Touch ID. Note you can only add a maximum of 3 finger prints.

Use Touch ID on Mac

And while one is at it - User profile showing Big Sur 11.6.

If this is accurate and correct - there are two more updates to Big Sur.

The latest version 11.6.2 was released December 13, 2021