There can be a lot of reasons to change a device and as long as it doesn’t effect he safety, efficacy or performance of the device, there shouldn’t be too much of a hassle to change it. Reasons to change a device can be a little as rotating the image of the logo on a device to make it more aesthetically pleasing or it could be an actual change to the device to make the efficacy better.In order to accomplish these changes you will have to supplment the PMA or offer a special 510k to the FDA.