I have eu keyboard and i don't have the little thing i need to press to switch between mobs and i want to know if there's anyway to change the controls

As Morph has just been rewritten and released for MC 1.16.5, I am clearing the issue tracker as I have not provided any support Morph for 1.12.2 and earlier. My apologies for not addressing your issue.

Bit late on this, but have you tried hitting the last few keys near the enter key? the keys where [ and ] would be on a QWERTY keyboard.