Hi Vishal, Hope you are doing great thanks for waiting the update. Please download the latest version of Education WordPress theme from Themeforest and install the update to your server.
Once you update the installed theme on your server you will see the fix of navigation in all devices. And all types of headers are working fine.
Make sure you update your cache if you have installed any cache plugin. Also use CTRL+F5 to load your site if you do not see the change after updating the theme.
Please watch this video how you can update the theme via FTP thanks.
https://youtu.be/ELtrCSa05J4
Thanks.