When in manual mode, you may want to disable the effects that are assigned to the amp models. You can do that by pressing the 'preset' button and navigate with <-> arrows to 'setup'. When seeing 'setup' in the scree, use the up-down arrows to go to 'AutoFX'. Use the 'preset' button (by turning it) to change it to 'Disabled'. Now you can change the amps without the effects changing with it, ideal for exploring the amp models in a 'clean state'.