@dborowsk - It sounds like your boards “Team” share permissions are set to allow team members to view, comment, or edit boards, so this is expected that “board” permissions are overriding “project” permissions. The only time a project permissions override board permissions is what you are not sharing the board with the team or a member(s), but you have set the project to allow one or more member to access any boards that reside in the project.

If you haven’t already, I would suggest that you change your default board and project sharing settings so that only the person who created them can see them - more on this here:

https://help.miro.com/hc/en-us/articles/360017572174

Is there a way to change permissions on multiple boards?   Like, lots of them?!

Unfortunately, no. You may want to upvote this Wish List idea: https://community.miro.com/ideas/multiple-boards-selection-5119

You can also post your own Idea in the Wish List category by following the guidelines here: Wish List: Everything You Need to Know.

If you do create a Wish List Idea post, I would also recommend that you post a link to it back here, so that future readers of this post can quickly get to and vote for your Idea.