How to change Text Buttons Like Sign Up

Hi,

How to change some buttons text, some of them is possible to edit but others like sign up on newsletter at the bottom of page and the button Search Tours on search menu on top of the page i cant find a way to edit.

Plus, the menu search tours have placeholders on textbox like Tour Name and Tour Type and for last Destination, how can i change them? And the months names to another language. If i need to change then in code please can you tell me the file?

If i edit this file, then on auto update theme with enovato updater the file will change again to default?