Thank you for the advice! This is my first time doing a game with UI as a heavy aspect. I knew it was a bit awkward to select them but I was running out of time to change anything about it. If i ever update it, I might make the selected trooper change to your most recently bought one automatically so you can go immediately from buying to spawning while still being able to select if you need to change.
As for the 2 screens, I'm not really sure how I'd fix that. Technically you can play the game without the bottom screen (UI for health would have to be adjusted) so it's more just there to make it fun to look at when you're able to. I found that I would look at it mostly when he was overwhelmed with enemies or when I didn't have any energy to summon new ones. Maybe the issue was a bit worse with your strategy since Trappers aren't meant to last very long, making you have to respawn them often.