Q: iPhone 6s ios9.3  I can't used the App Store or update my app??

Hi adynorway,

I understand that you are unable to update apps or access the App Store on your iPhone 6s. Let's see if we can get that sorted out 

Now I know the article below refers to issues with connecting to the iTunes Store, but the steps are relevant for the App Store as well. I would make sure that the Date & Time is set correctly or set to Automatic. 

If you can’t connect to the iTunes Store
https://support.apple.com/en-us/HT201400

Have a good day

Hey adynorway,

Glad you got it sorted out by updating your iPhone. 

Thanks for using Apple Support Communities. 

Take it easy