iPhone Apple ID reset Can I reset or use a new Apple ID in my existing iPhone? Will it affect the existing apps installed? 

Sorry I’m kinda new in the Apple environment and my sister just gave me her old iPhone.
Here is the playbook for wiping the iPhone before you put any information on it. 


https://support.apple.com/en-us/HT201351


If you don’t detach the previous owner accounts, your data will commingle and you’ll eventually need their password or potentially be locked out of your phone. Search more on this site for all the woe people experience trying to bypass activation lock and untangle commingled address books, calendars, App Store purchase, etc...

Unless that device has made dozens of previous AppleID, you will be able to make a ne Apple ID once it’s erased. Just follow the “make an AppleID” prompts when you set up the device after the wipe (which wipes everything on that device but nothing stored in the cloud)