Iphone wont connect to itunes
I keep getting the error
"The Iphone "Jenifer's Iphone" cannot be used because it requires a newer version of Itunes. Go to www.itunes.com to download the latest version of iTunes."
Okay at first this IPhone 6 plus belonged to my mom and it connected and synced up to itunes version 12.1.2 for windows 8.1 perfectly fine on my laptop. She gave it to me so I restored it! Its updated to the latest as well, but when I try plug in the usb On the same laptop and itunes version, I get that message on itunes. So I check for updates on itunes and it says its up to date. I went to the itunes webpage and says the latest version is 12.3.3 so I donwload it but when I try to run set up I just get another error! Saying I can't run this version!
What can I do to fix this please and thank you. It worked fine before.
iPhone 6 Plus, iOS 9.3.1