I bought one of those (identical to the one in the original post picture) and it works great, but the user manual has the same information for the stitch width and stitch length, so for my mom I just put a piece of office tape next to each selection knob with width on the top central one and length over the other to the right.
https://photos.app.goo.gl/jg7C2qbCNUaA7PBH7