Q: Apple ID

In what way are you being instructed to change your Apple ID ?

So you want to change the apple ID logged into on a device ?

I do not believe there is a way to do this without losing access to your purchased material. I strongly believe Apple should allow users to merge Apple ID's as I also have this exact same problem .

Very sadly there is no way of doing this and I strongly agree that this is unfair on users.

You can't get a new apple id and move purchases from an old one to it. Those purchases will always be tied to that apple id.

I'm not sure what you mean be changing your apple id for security purposes. If you feel your id was compromised, then change the password.

If you want other users to view your purchases, then there are several ways to do that. You can do sharing with iTunes. You can also use family sharing where the main account holder is responsible for purchases, but other can view all your purchases while still having their own ID.

It also depends what type of purchases you have. If it is apps you are able to set up a family and this will allow you to share some types of purcahses with the other Apple ID. This doesn't transfer the purchases only share them.

Never said it would transfer purchases. All purchases made from an apple id are tied to that id and can't be transferred.

Most purchases can be shared with family sharing. Only a few exceptions apply:

What types of content can I share with Family Sharing? - Apple Support