Show/hide acting globally

[dyounglas]

I have a Trello board I use for my weekly schedule containing Monday - Sunday lists. I have a template board I copy each week as the basis for the new week's board. I just noticed that when hiding days (lists) on one week's board, they also become hidden on every other past week's board as well. However, if a board has a custom list created, it is listed only on that week's board and not all the others. Is this a known issue? Could it have something to do with copying previous boards as the basis for the new one?