This may seem remedial but double check your keybinds in settings. A lot of trainers and such make use of the F-keys which are usually character selection/change in Story Mode
This may be an inopportune time to ask, but why is "One Hit Kill" so hard to find in a good trainer these days?
I found this very simple black & white one that stays top left. I believe Trainer V is the name - I LOVE how you can save changes to a config so you don't have to set it all up next time! Unfortunately it doesn't have that option (one hit kill.)
For me, I love to have the menu memorization (you use "clean player," you hti that menu option, "clean player" is the first one highlighted,) the config / save option and One Hit Kill. I think the teleport quality also determines a good trainer.
To get all that into one, as well as some recovery options (including misc - clean player, use that a lot,) like "unlock all...," I'd donate as well