Customize Site form

Frappe Framework
1

Hello ,
on the my site i changed the Footer.js and removed the tags and assign to sections.
some times i use frappe --sync_all to upgrade and validate the sites .
when i do that all the changes erased and use the default frappe form .
my Questions
1- if i changed on site files should i stop using frappe --sync_all ?
2- when i make changes to .py files what should i do to make active ?
3-when i make changes to .js and .html files what should i do to make it active ?

thanks

2
  1. frappe --sync_all will sync the DocTypes with the database
  2. frappe --build will build CSS / JS files
  3. frappe --latest will run patches (if any) and build and sync

If you using frappe --serve, .py files will automatically refresh.