Hi Karen…the logo sits in a container (box) that has a certain size and the navigation to the right of it also sits in its own container. This theme is responsive, so the width of the logo container will constrain the logo you use and will size it down if the logo is bigger than the container. You have two options:
1. switch to the child theme for Encounters (if not already using it) and edit the header.php file
2. change your menu to go into the secondary menu location which then gives you a bit more room for your logo
Option 2 is done from the Appearance >> Menus >> then choosing secondary location for your menu settings. This is a full width position that goes below the logo and across the top of the showcase banner area.
Option one means installing and enabling the child theme, copying over the Encounters header.php (upload) to the child theme, then change the container classes of span4 and span8 for both the logo and the nav containers. This is similar to this post:
Change them to be span5 and span7 respectively. When you add to one, you have to take from the other.
The span classes refer to how many grid columns each container takes up. So a span5 means it takes up 5 columns and the other takes up 7 columns so that both side-by-side total 12 columns (which the theme page is a total of 12 columns wide).