EDIT: The title is supped to say "editing properties on mac. not preterites"
So, i need to edit the properties of a program (Mumble) so i can run two mumble windows at once, i did some research on this, but im only finding how to edit them on windows. Here is what i need to get to on my mac, but the windows version:

i need to go and edit the text of the highlighted section. But i can not find how to do so on my mac. if you can not read the highlighted part, it says:
"C:\Program Files\Mumble\Mumble.exe" -m
The normal text for that would be
"C:\Program Files\Mumble\Mumble.exe"
I need to add that "-m" extension so i can run the program twice on my computer, if anyone could help me out with this, that would be great!
So, i need to edit the properties of a program (Mumble) so i can run two mumble windows at once, i did some research on this, but im only finding how to edit them on windows. Here is what i need to get to on my mac, but the windows version:
i need to go and edit the text of the highlighted section. But i can not find how to do so on my mac. if you can not read the highlighted part, it says:
"C:\Program Files\Mumble\Mumble.exe" -m
The normal text for that would be
"C:\Program Files\Mumble\Mumble.exe"
I need to add that "-m" extension so i can run the program twice on my computer, if anyone could help me out with this, that would be great!