You may need to go slow but be consistent. I don't see how old he is, but perhaps you could also try some other reward besides treats to start. Once he 'gets' the first command you teach him, he may surprise you by eagerly wanting to learn more. But, the more consistent you are with every 'command' you use, the quicker he will pick up what you want him to do. Lots of praise and kisses and 'good boy's'
the instant you see he is doing what you want, even if he did it on his own....which is a good, subliminal way to train...and say nothing when he isn't doing what you want...ignore...walk away, etc. In other words, when you see him starting to sit, be ready to say the word "sit" the instant his butt touches down and praise him for doing it...for being 'good'. If you want to treat on these occasions, just carry around some treats that he isn't given...even though he continues to smell them...UNTIL he does something YOU WANT HIM TO DO.
It isn't going to happen overnight, but you can help him learn. Good luck!