Limit of free accounts on iPhone

You can only create 3 Apple IDs on an iPhone for the lifetime of the device. There is no way to change this. If you want to use a different one you will have to create the Apple ID on a different device then sign on with it on your iPhone. Why do you need so many Apple IDs?

You can login. But you have to crate your 4th account on your computer or some other device. Again, why do you keep creating new accounts?

No, this is a user-to-user technical support site operated by Apple, I have no interest in dm with your. If you cannot state your issue here click on the Get Support link at the top right of this page and contact Apple.

What do you mean be activate the iCloud? What does this have to do with creating a new account?

What is dm?