How do I change my current apple id on my iphone to another to allow me to change that other apple id password? Thanks

If you need to change the password for a different account and you are using an iPhone, do so on the web.

Change your Apple ID password on the web

1. Sign in to appleid.apple.com.
2. 
   
3. In the Sign-In and Security section, select Password.
4. 
   
5. 
6. Enter your current password, then enter a new password and confirm the new password. Forgot your password? 
7. Select Change Password.

From: Change your Apple ID password - Apple Support