Because this is a big update (I suspect) I think it might be best to go to settings and update and security and press check for updates button, it should install it then and give you the option to restart. For some reason it seems when you go to update and restart it's not fully updating it? If it doesn't work go here:
https://www.microsoft.com/en-gb/soft...load/windows10 and press update now, it will download a program to do the update.
Also when it's finished updating run disk clean up and remove the old version of Windows to get some space back (you can safely tick everything)
They probably changed some things around with 360 security, of course the free versions are still usable with Windows 10. Theres an upgrade button on my anti virus too because I use the free version and they want you to upgrade to the paid version. You can usually find the current version somewhere in the program.