Toyota uses a thread sealant when installing ball studs and many other parts on the vehicle. The easiest way is to soak the area with a good penetrating oil at least 24 hours before you start your project. Or you can heat up the stud using a hair dryer, or some other means just get it warm, no need to get it "Red" hot. If using heat after you used penetrating oil make sure that you clean the area in the the penetrating oil is usually flammable. As a safety measure always use eye protection while working on the vehicle.