Emuelec 4.2 setres.sh

I have made A new install of emuelec 4.2 on a 32 gb card
But now I have the same problem as my old 3.x install
Screen overscan.
When I try the same method i used on the 3.x version by modifying setres.sh, I get the error the file is unwritable.
Copy the file to another location as suggested by ShantyGilbert make the file editable.
But when i try to copy it back to the original location i cannot overwrite the original setres.sh
I have set the file attibutes to 777
I am hoping somebody can give me a tip how the overswite the original file with the new file