Absolutely. In fact, they are designed to adjustable because you are going to have to do a bit of adjusting. This is especially true with the laser parking aids as well as the ultrasonic ones. Essentially, you will need to get your car into the perfect parking position before setting that data into the parking aid itself. These style of devices need that reference point in order to help steer the vehicle back to that sweet, sweet perfect parking spot.
Even the low tech devices will require a little adjustment, although usually not as much as the higher-tech models we discussed above. Adjustments can usually be made multiple times, but devices that are secured with screws should be positioned correctly before you secure them with permanent fixtures. It could be a good idea to invest in something like 3M Command Strips. Use them to position the parking sensors, and only once they are in place to perfectly guide the car should you secure them with permanent fixtures like screws.