Dogs are pack animals in nature. Even when they're domesticated they follow this behavior by instinct. To get them to listen to you need to position your self as the alpha of your pack (family). Their are several ways you can try to do this.
-Your tone of voice
You should give commands in a firm, authoritative voice. Dogs pick up on subtle things like voice inflection and body language. Act as if you expect these commands to be always followed. Do not beg or try to bribe them.
Dogs love getting praise. Telling them they did good when they follow a command or giving them a treat can be very effective.
This is especially when you are not the only one training your dogs. You need to give the same commands in the same way always. You need always praise them when they do the right thing. If you scold them you need to always do it when they misbehave and always use the same phrases
Training can be very difficult and requires a lot of patience. You want to start training your boxer as soon as they get to be around 8-9 months old. The longer you wait after that the more difficult it will be.
If you need help you may want to try an obedience class or one of the many books on the subject.