If I use a theme sitewide and it doesn't have the option to swap the logo out, how can each sit

I'm using Gallery Theme. I can't find the option to change the logo. I'm assuming that this means that I have to overwrite the logo that comes with the theme.

This means that the logo would change on all of the sites within my network. Obviously, this woudn't do.

I've checked and this theme is buddypress enabled.

Please help.

Regards,
Sonny