It's your responsibility to ensure that you update your firefox browser to the most recent version, you can always find out that information by going directly to the firefox website.
It will not automatically update sometimes from an old version, you will need to manually go to the website and select the latest version update. It will retain all the settings and stuff. I use xmarks to keep all my favorites safe and updated. That way should something go wrong I won't lose anything.
You can also backup your favorites manually.

I always just go to the Help tab at top left of any FF page, click "About Firefox", and it automatically updates me to the latest version.

Currently 17.0.1.

I have the current and always update it when there is a new release. I was just curious if my Pc Was an Xp or older would I still be using 17.0.1 I read this week where people are updating to to 8 , 12 etc.. Maybe I just stumbled into some outdated discussions.

The automatic updating for FF depends on the configuration.

Tools>Options>Advanced>Update tab>user determination.

DA

I set it to alert me when there are new updates. I don't automatically update most things.

FF 18 should be going from beta to being the latest standard download within the next two weeks.

A futuristic view is a new release every six weeks. The last date I saw for v18 is the week of January 6th.

DA

FF 17.0.1 and Silverlight and Netflix have some sort of annoying comparability problem. If you stream Netflix figure out how to avoid 17.0.1 or use IE for streaming.