Nav Menu & Sidebar Widgets

Is there a way to set a static width for the nav menu at the top of the page? Right now, depending on which browser you use, 1 or 2 of the tabs will drop to the next line, and I would like for them to consistently stay on a single line.

Also, I have quite a few custom sidebars being as each page requires a separate location/phone/hours of operation. I have text widgets placed in each sidebar and for most pages they work great. But, for a few others the custom sidebar I pick from the drop down menu will not stick. Each time I update the page its goes right back to the default sidebar. Is there a way to fix this?

Thanks so much!