automatically assign the accounts contacts to the account owner

I bulk updated accounts to assign users. The accounts contacts owner (Assigned to) did not get changed which means the new owner cannot see them.

How can you automatically change the contact owner based on the accounts owner?

SuiteCRM version: 7.10.6

you can try to create a workflow for this. No coding required!

Otherwise, if you want to do something more sophisticated you could write a scheduler or a logic hook. But for these you will need to write some code.

I looked at the Workflow configuration and it is not very clear how I might update the Contact Assigned To field to match the contacts parent account Assigned To

You might prefer to do it directly in the database with phpMyAdmin and SQL. But be careful and make backups first.