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

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

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.