Featured Content Gallery : only 3 page IDs to display

[sebmilo]

Hello guys,
I'm configuring the Featured Content Gallery on homepage.
I don't choose a category selection because i' dont do a articleimg for all my articles
Finally I choose the option : "Select here to use individual post or page IDs "

In this case, I write all Id's of my article with an articleimg.
I have select "Check here to randomize post/page ID display " for randomize the home page display.

But I have a little problem due to the number of articles and the loading time. In fact, I want only 3 articles randomize in my homepage gallery and if configure "Number of Items to Display" with 3 for example it's don't work.

Can you help me please

Thanks for all

PS : an other question, i want remplace my RSS original URL with my new feed with feedburner and i don't find how to change