A lot of time brake levers are fitted in a wrong position. To correctly determine the position, place your hands outright as if you were riding the bike. The correct amount of fingers should fall onto the bladed part of the brake lever. If it doesn't, then we need to make adjustments.
Adjust the brake lever by loosening the allen bolt. Make sure the brake is in line with your arm's position when your hands are on the bike. Once you determine the correct position, then tighten the allen bolt.
When choosing shifter position, make sure you are able to control the brake levers without interference. Then find a comfortable position and tighten the allen bolt. You want to be able to shift while also being able to control the brake lever without moving your hand.