Hyperactivity...having trouble managing it

I have a Flat Coated Retriever mix and he´s 8 months old. He´s a rescue dog who had absolutely no rules and we´re having trouble controlling him.

We´ve tried training him on a serious problem which is jumping on people because he gets too excited. He does a great job when theres treats around but as soon as we end training he goes back to the same and it´s exhausting.

We sometimes watch videos on how to deal with it but he´s a big dog and the "shushes" and small touches don´t do anything, he just keeps jumping on me and other visitors.

His leash walking isn´t good as well but its almost the first time he´s ever walked with it so we´re not very worried about that.

Another thing is that at around 7am he just starts barking and we have no idea how to stop it.

Would love some help on this hyperactivity please!