The best thing is to create many small successes and really build them up. You attended a contest and got 1st place in your devision? (of 1 band there) Better take that trophy and take a huge picture and send it into the local paper as well as get a huge cake and celebrate.
The best way to change a band culture is to have them buy in to getting better and better through small successes.
The way to change a community is to send home happy kids and post tons of things on a school social media page and in the local paper. then do this for a few years.