Some brands of patches stick better than others. Estradot have a good reputation for sticking well and are definitely sticking to me with no probs, including in the shower. (Have not tried bath or swimming yet!)
So if you can't get yours to stick perhaps switch the brand of patch.
Meanwhiles - make sure the skin is bone dry when you put them on, even if you have to use the hair dryer to dry your skin a bit! Press your hand onto the patch for at least 10 secs after putting it on. Don't use any body lotions or moisturising shower gels etc on the spot where you put them.