How do I change the default configuration of MPlayer movie player?

[Steven Vollom]

> With your file manager right click on a movie file and select properties.
> Click on the button with the wrench icon beside the file name. There you
> can add Mplayer (if necessary). Then move the Mplayer line to the top 

What did that accomplish?  When I then clicked on a movie it still defaulted 
to kaffeine.

> make it the default. 

Where is the default option?

> Click on the modify button and select the program tab.

Since I made the recent changes, I click on SystemMenu and it opens, however 
the choices within the menu will not open.

> Probably the command is "mplayer %u" or something similar. Change it 
> to "mplayer -fs %u", i.e. write "-fs" after "mplayer". Then Mplayer will
> always start in full screen mode.

Nils, if I typed in mplayer -16:9 %u would that default the aspect ratio to 
16:9?