After you have created your webinar, you can update your logo in two places.
1. Click the Design tab of your webinar dashboard:
Once you have accessed your Design tab, click the "Conference Room Branding" subsection and select "Change Logo" from there.
Note: if you save the theme as the default, all future events in this channel will use this theme.
2. Inside the live webinar room:
When your webinar is in progress, scroll your cursor over the logo in the upper left-hand corner.
Click EDIT THEME.
Then edit your theme color.