Problem after rebooting

Hi all.

So the situation is that:

I've a FreeBSD 64bit OS on a VM (virtualBox). It works fine, zero problem. But when I modify something, and I reboot, I lose everything.

I've searched a lot for a command like "save-all" but nothing.

I hope you can help me.
Let's start with some basic information: what version of FreeBSD? What version of VirtualBox?

Then we go to specifics: What do you modify? What do you use to modify it? How do you save it?
Not sure if I can help but I got FreeBSD 10.2-RELEASE running emulators/virtualbox-ose version 4.3.36. On that I have a Linux Ubuntu (guest) server running, and a FreeBSD 10.2-RELEASE (guest) running at well. I don't think I am having that issue. But I will willing to try and copy what you are doing.

Answer wblock questions first at least. :)