Go to
Preferences==>Window Specific
and unselect
JSL Scripts should be run only, not opened, when selected from Recent Files of a file browser
You can also stop this behavior by pressing down the CNTL key when selecting from your file browser
It may also be that someone has placed "//!" as the first line. This will force the running of the script rather than opening it. Pressing the CNTL key when opening this file will open it rather than running it
Jim