[AC Question]

Somebody else has read mmy texts from another device how do i find out and disable it

[jasonandrews25788]

from the app manager check if there's a suspicious package installed on your device and delete the browser cache and data.

[B. Diddy]

Welcome to Android Central! Do you know for sure that other person can see your texts, or is this just a suspicion?

[smvim]

Somebody else has read mmy texts from another device how do i find out and disable it

Log into your texting service user account and change your password. You need to regain control of your own account and deny them any further access to it.
As for the title of your posting, there's really no 100% way to check if you phone has been compromised, today's black-hat hackers are most definitely not the stereotypical kids working out of their parents' basement, a lot of them are well-trained, highly paid, and typically develop very hard to detect and/or remove exploits. Most of the time you find out there's a problem after-the-fact.