Amending menu button size

Hi guys

I am wanting to extend the size of the menu bar on this website:

https://www.joinerybuildingsolutions.com

At the moment (on portfolio link) some links are spread over three lines which looks horrible.

I have tried changing the colour also, but would like a different colour highlighting option to select.

Finally when you click on portfolio the menu goes to the side rather than down.

Any help would be appreciated

Thanks