Hi culfytt, the ‘learn’ menu button depends on having rotary encoders available to your zynthian (such as with a kit). The instructions for midi learning in the wiki are aimed at this. I should add the information about mouse and touch because it gets asked every now and then.
You can look at this page: Midi learn with mouse
The summary is: try (with either mouse cursor or the touchscreen) click/press starting from left side and dragging to the right inside the parameter box area of the screen. This skips the first step (all parameters show ??) and makes the parameter ready to assign immediately (which is what you want when you have no encoders) I am able to do that successfully most of the time.
As a side note I think the ‘learn’ function goes through two steps now, first is green, second is yellow. I think this is a new thing in Oram, not quite sure how it works yet.