Hi all, I hope someone can help me as this is making me anxious.
I Just noticed this in the Tor manual: “Unlike in Tor Browser for Desktop, the “NEW IDENTITY” button in Tor Browser for Android does not prevent your subsequent browser activity from being linkable to what you were doing before. Selecting it will only change your Tor circuit.”
How do I make a new identity that isn’t linked to past activity on Tor mobile for Android?
Thank you.
You have to close and reopen for unlinkable new ID
Do you have a source for this?
"If you are keeping Tor Browser open and running then you will be trackable from day-to-day and between visits, this is because it is data associated with the state of the browser that is trackable, it is not related to Tor’s circuit choice (which will be different after 10 minutes of no new connections being made to the site in question).
You should consider a “session” as a period of time between when Tor Browser was last started or the last time that New Identity was used until it is closed or the next New Identity is issued. During any sessions the site you are visiting will be able to link your session together regardless of the circuit you’re using or how long the session is, this is intended functionality of web browsers."
From: configuration - How set Tor browser to use new identity on each session - Tor Stack Exchange
Also remember that Tor along with all encryption algorithms will soon be broken so whatever is making you anxious will still be known regardless of anything
The fact that Tor Desktop does create a new identity with request is a good capability which I would like to see crossed into the mobile app, but can someone please tell me if I remember wrongly; its been a while since I’ve used desktop. I think I remember in desktop if you click new identity it changes just the exit IP and if you click new circuit it closes and reopens the browser. I guess restarting the app is the mobile equivalent of new circuit?
Never mind, I’ve just managed to figure out my own answer 
" NEW IDENTITY
This option is useful if you want to prevent your subsequent browser activity from being linkable to what you were doing before. Selecting it will close all your open tabs and windows, clear all private information such as cookies and browsing history, and use new Tor circuits for all connections. Tor Browser will warn you that all activity and downloads will be stopped, so take this into account before clicking “New Identity”."
From: MANAGING IDENTITIES | Tor Project | Tor Browser Manual
Tor Browser Android will automatically close all windows and tabs, deletes cookies and any other form of identifiable information when stopped/closed
The answer given by @snizz has proven correct