Generally speaking, the prescription on your lenses should be made exactly the same as your prescription. You'd better take them back to your eye doctor and check if they have done with the wrong prescription.
It will make you look strange if you wear them upside-down. Maybe your prescription has changed. Try wearing your new glasses. If there is no problem, then you are safe to wear them alll the time. If you find uncomfortable to wear them, you should take your glasses back to your doctor to have the prescription re-checked.