u/Beginning-Middle-461

Hi everyone, I play Xiaoyu as main. I'm new to Tekken 8 but used to play her in TT2 and 7. Sometimes in the middle of a fight, her buttons will suddenly change and the combos and inputs I was using are completely different moves/limited to a few moves. I don't understand what is happening or how to revert back to how she normally plays. I think I must be pressing something by mistake. It's costing me matches and I have to reset the game to switch her back. Can anyone understand what I mean, and how to switch back mid fight? I can't find any clear answers. Would greatly appreciate the help, thank you.