The Kaleidoscope theme in Wild Apricot is beautiful! Changing the main menu design though is not something that can be done by pointing and clicking. You need to use CSS to modify the menu. This snippet of CSS code will help you modify the main menu in Kaleidoscope and Bookshelf, two themes that share the same menu styles.
Step 1. Download the CSS code
Step 2. Use the Website > CSS option to copy and paste the CSS code, or use the WebDAV approach to create or edit the user.css file.
Step 3. Modify the various color and background options to your heart's content until you have the menu working just like you would like.
Hint: Popular colors are available online at W3Schools. You may wish to use your own hexadecimal colour values that start with #.