When you say patch, are you referring to a synth patch? If that is the case then this is how the Synths work on the Play+. You cannot have a different patches on patterns (or variations or steps)
If you change a patch on a synth engine it will change for all the steps, variations and patterns assigned to that engine.
The workaround would be to use a different synth engine.
Thanks, now I understand. I thought I was going mad. But I am sorry to hear this. I thought to build up songs by changing the patches on each variation or pattern but now I am limited to one patch per synth. I guess I am just going to have yo use more samples.