Z-Index with Sub Menu

Z-Index Main Nav Sub Menu to the Front

Hello and thank you for the awesome support! We’ve updated the HighEnd theme to the latest version. Upon doing so, we’ve had to adjust some styling issues. We previously added a custom menu that sticks to the top and overtops the Main Nav menu. Before scrolling, you could access the Main Top Sub Menu, As you can see below, the Main Sub Nav sits behind the purple menu without scrolling. This used to work in the previous theme but it no longer works currently:

If you look on this page, you can see the top Sub Nav Menu sits behind the purple menu without scrolling:
bestbuddies.org/florida/donate
snipboard.io/ke7dXP.jpg

any advice would be appreciated. Thank you