If you want to change the right hand tone, then you would need to disable split, at least temporarily. After selecting the new right hand tone, you can enable split again.
If you know what kinds of setups you want to use in advance of a performance, then you might find it easier to save some setups to registration memory. You can create setups which are similar, apart from the right hand tone, and then save them to different registration areas in the same bank. You could then press a single button to change between the registrations.