If your e brake is working properly, and with at least one rear wheel on the ground, unless you're The Hulk, changing a tire should not be such an undertaking (no pun). It soulds like the e brake is slipping or at least not very tight. Remember, the e brake has less of a grip with the car heading up a hill than the opposite. Also, remember to break loose the lugs before completely raising the tire off the ground. It sometimes takes a lot of torque to get those lugs out and with the car perched on a jack, it is probably possible to get it to move or even fall over. You can exert a considerable about of leverage on those lugs. Another point to be aware of. The jack is designed to be inserted in the jacking point at an angle. That is to say the bottom of the jack is actually contacting the ground at an angle and if properly set up looks kinda weird. The top of the jack angles away from the car. When the car is jacked up, the angel becomes more perpendicular and looks right. Overall, you have to decide what feels comfy to you. I've used this jack without problems until my son decided to jack up the front end of his Explorer and broke the damn thing. Oh well, he said he was sorry.
Remember a jack of all trades is not in the trunk of your car.