Hey, thanks for playing.
Options menu contains only default binds for skills - those which are used when growing new zooids. If you have already grown a zooid, it has to be changed in Growth mode.
You can do that by:
- Entering Growth mode
- Clicking Right Shoulder on controller (I might be remembering the bind incorrectly) - One of skills will be selected
- Use Thumbsticks to navigate to appropriate skill and press A to enter rebind menu.
When you are using controller there should be a navigation help menu appearing at the bottom left

Let me know how that works out for you