The only bolt you should have to loosen is at the pivot point of the stem (with the black washer around it in the picture). You may have to use a wrench from each side to loosen it until the stem moves easily. Position it at the desired angle and retighten. You may also have to loosen the other end of the stem to readjust the handlebars once the desired stem angle is set.

Randomly "loosening stuff" is rarely productive.