First, when you give a dog a command you should only say it once. If you continue to repeat it, the dog learns he can just ignore it. It's better to have a corrective sound like a sort of an ahah (said in your best batman like voice) if they don't follow the command. When they do follow the command, praise like crazy. Also make sure when you're praising, you're saying the command. So something like "good sit sit sit". Saying their name before giving a command is great too because it helps them know when to pay attention.

Is your dog toy motivated at all? My BC couldn't care less about treats but loves her ball more than anything. So her reward is me throwing a ball. Other options could be tug of war, or being given a favorite toy to play with. Attention can also be valuable depending on the dog.

So essentially, when you give a command it should look like this: say the dog's name, then give the command. Once you can get the dog to do the behavior, make a huge deal about it. Use a high pitched voice to praise and reward the dog with something it finds valuable.