ANSWER:

You must say SamiAllah huliman hamidah while rising up from ruku and not Allahu Akbar. 

Your prayer is valid due to your ignorance. However, if you continue to do this deliberately, your prayer is invalid.

QUESTION: Will saying Allahu Akbar after saying “Subhana Rabbiyal Athem” make the salah invalid? If so, does that make all my past salah invalid, because I didn’t know but when I knew, I wasn’t sure whether to trust it or not so I still say Allahu Akbar? When I researched, I saw that it was still valid to say Allahu Akbar and my mother said to still say Allahu Akbar.