How can I change my password?

I keep forgetting the one that was generated for me,so I would like to have my own choice, but I can't figure out how to do it. could anyone give me details,please?

 

im on mobile at moment...but if the layout is the same....click avatar next to message box top right of screen...scroll to bottom of list and you will see password...click and follow instructions to change

 

If you select your avatar (top right) one of the options is password.

 

Beaton by a split second.

 

Thanks everyone. Done