Vim: No write since last change, even though I changed the file

Try this, after editing your file, quit with this command: wq!. the ! means force the process, and when you combine it with wq that means force to save and quit.

The error message     "No write since last change"    that you encounter basically means that
you have not save to your file since the last editing, the write here have the same meaning as save.

If you want to save and then quit VIM, type the following
:wq Enter
or
you can also type the following
:w Enter     <-------- This command is to save the file
:q Enter     <-------- This command quit VIM

If you want to quit without saving any changes, type the following
:q! Enter