Remember changes

android

#1

hi everybody i have a quick question in connection with android studio, im making a app for school but i have a problem where i cant solve it myself, so the problem is that,

if I click on back (a button in second activity) from my second activity I have to go back to my main activity (I did this), but if I go back to my second activity everything is back as it was in the beginning, what I want is when I change something in my second activity and go back to my main, everything that I have changed in my second activity must stay as it was when I changed something, and when I go back from my main to my second, everything that i changed is still there.

i hope you can help me, thank you in advance.

this is mij second activity class code

and this is mij main activity class code