I will be traveling to China in May. I am 54 and this will be my first travel outside the US. I think I have done everything to prepare for the trip. However, I have questions about going thru customs when arriving in China. I have read a lot about what has to be declared but I am really confused. Do I have to declare my laptop, iPhone, iPad, apple watch,and mophie battery pack?

These are all personal items and you are not importing them into China. You just walk through the "Nothing to declare" green exit. You may have to put your luggage on an x-ray machine on the way out.

For internal flights within China we were told various things about what could/could not be in checked and carry on baggage. We must not have heard it right, because our portable battery chargers were confiscated from our carry on luggage. We were told that we could have them in checked luggage . I thought that I read that batteries must be in carry on. I had batteries AAAs for my noise cancelling headphones in my carry on luggage and that was perfectly fine. I think I did have to take my ipad out of my carry on whereas in most places in the US you keep it in the bag and just remove a laptop. They have plenty of signs for this info at the security points.

Just walk through Nothing to Declare for Customs. You will need to obtain a Visa to visit China, to go through immigration/ passport control, but it is now good for ten years, an improvement.

Not something new but more important only for Americans. Canadians get "up to" 10 years. Have no idea of the OP's nationality.

Well, the OP says he has never been outside the USA. So maybe he is an AMERICAN.