Respuesta :
This depends on the if the screen wirter sells the script or not. If the screen writer sells the script then yes, the director can change the script and how much, but a screen writer can sign a contract where they still own the script, but can determine how much of the script a director can change within the script to none at all.
I hope this helps answer your question.
when screen writers sell their scripts their contracts and/or terms of conditions will often include how much the director , producers , executives can change. but of course if the screen writer agrees with them then the screen writer sighns the contract