Hi,
Please check the documentation to setup the main primary header menu
https://www.gracethemes.com/documentation/pubstore-doc/#menu
To change the background border color of services boxes
Go to the Appearance -> Editor -> style.css file
add below css code at the end of file
.threebox:hover .thumbbx { border-color: #000000 !important; }
It is not possible to change the space of boxes as it is already displaying fine.
Regards
Grace Themes