How can I Sign in to the iTunes Store on my iPhone 6s

Settings ➜ Apple ID ➜ Media & Purchases ➜ Sign out and then Sign in (or only Sign In if no account is currently signed in).

lat272 wrote:

please, tell me about how to sign in iTunes Store details?

ref:

Sign in to iCloud on all your devices

If you can't connect or sign in to iCloud

If you can't connect to the App Store, iTunes Store, or other Apple services

If you see "Cannot connect" - Apple Support

There should be an iTunes Store app on your phone – separate from the Music app.

This is different from the arrangement on Macs, where the iTunes Store interface was originally part of the iTunes application, and is now part of the Music application.

lat272 wrote:

I want to update ios16.0

You will need an iPhone 8 or higher model to update/install iOS 16.

The current iOS 16.7.7

ref:

About iOS 16 Updates

Update your iPhone or iPad

 The current stable release of iOS including bug fixes,  security updates is iOS 17.4.1

Go to settings - general - software update and start there.

6s is using more apps