Regarding to my personal experience, the contact will move in your eyes when your eyes are dry and hydrated. So you need to find the right eye drops and drink lots of water. Also you could have things in your eye that you don't see so no matter what your contacts won't feel right. A bad pack? It happens try using the next pack. Take the contacts out flush out your eyes and wear glasses the rest of the day. The contacts might just be really dry. Get some hardcore drops too that really flush your eyes out like one of these brands, contacts can be a real painful bitch you have taken care of your eyes and what you expose them to. Hope this helps!
In fact, it is normal for the contact lenses moving in your eyes sometimes such as when you blink eyes. But usually, the contact lenses only move in a very slight place and don't affect your daily life. But if you feel trouble of the moving contact lenses in your eyes, you may wear the improper contact lenses. So, you'd better see your eye doctor to buy other proper contact lenses that fit for your eyes.
As we know, the contact lenses are worn directly on the eyeballs. Its water content makes it stick into the eyeball surface rightfully. However, your situation may be caused by the not appropriate size of contact lenses for you. You'd better change one. Or else, it may fall out of the eyes.
It will make you feel so uncomfortable if you are wearing a pair of contact lenses which are often moving around. So it is essential to take some measures to adjust them. maybe you can try to drop some eye drops to keep them from moving around. But in my opinion, you are not supposed to adjust them by yourself, for it is dangerous to make your eyes infected. And also, it will lead to some eye diseases. So to adjust your sunglasses, you'd better go and console it with a professional person. They can give you a professional service.
That contact lenses would move differently on eyes depends on their design. If you are wearing rigid gas permeable lenses, it lend to move more on the eyes than soft ones. Maybe you can change to soft contact lenses. Or if your lenses are too loose thus would move around your eyes, you can change another pair of tighter ones. That is to say, you could select one pair of lenses that are bigger than your eyeballs instead of just fit them. At the same time, they can prevent vital oxygen and moisture from reaching the eyes.