What you were expecting to happen, and what actually happened?
I wanted to change my guild war defense teams, I can choose another team; but when I go back to the GW defense teams list the old one is still there.
What are the steps to make it happen again?
Fix the problem ?
You should be able to on the GW Defense Tab, tap the team banner, pick a different team and it should save that. (Note it doesn’t save if you use the Edit Team button)