Personalize Theme selection

Hi,

System: EP6.0 SP15 - xyx:50000

Revese proxy : Apache web server - www.abc.com

I have designed seven themes and given to the user. my portal is accessible through www.abc.com/irj/.

when user goes to personalize and select theme , user is able to select theme out of seven. but when he save the theme it goes to xyz:50000/irj which is internal/Intranet url address. I want to move to www.abc.com/irj/ path(internet url).

Issue 1:-

I would like to know where I should change the path in EP so that save button direct to internet url which will be resolved in reverse proxy and diverted to http://xyz:50000/irj/

Issue 2:-

I would like to set a default theme so that automatically it will change all the live user's current theme

Thanks & Regards,

Sanjeev