Saving viewer preferences

[George Papen]

It appears that I cannot save "Acrobat" as the pdf viewer option. When go to Preferences/Conversion and
use open -a "Acrobat" for the Viewer preference for pdf, it works fine for that session, but when I quit Lyx and
start it back up, I get the following message

Unknown tag "Acrobat""' [around line 81 of file ~/.lyx/preferences

Is there any way I can save this preference permanently?