How do I change the user rating and/or number of votes?

Install the following plugin: https://wordpress.org/plugins/show-hidden-post-meta/ 

Now edit the hub page with the user rating and/or votes you want to edit and scroll down to the Custom Fields panel and edit the value of the _gp_user_rating and _gp_user_votes field.

If you don't see the Custom Fields panel, click the Screen Options tab in the top right corner and check the Custom Fields option.