There's several levels to this. The first one is pushing the content types down. You don't say if you're using a Content Type Hub to provision the content types but if you do then you need to publish the content types, then run the relevant subsriber job three times (I love SharePoint) to get them to take effect on the subscriber Site Collections.
The next level is getting the changes to roll down to libraries and lists. SharePoint does some very bad things here imo, when you use a content type in a library SharePoint creates a Child Content Type that is identical to the parent. This is why when you update a content type the libraries don't see the effect. The reason for this is so that if you were to have a document library with a content type in it, then change the definition of that content type, you might break things. By using a Child content type it makes SharePoint more resilient to change.
So what you need to do is make your changes and force those changes to roll down to child content types. To do that you need to use .Update($true) instead of just .Update()
Note that if you've got inheritance then you can have a lot of fun with fetching the latest copy of a content type depending on if its' parent has been updated or not. I've been working on this myself and hit issues on inheritance where it appears the hierarchy can cause updates to seem to fail. If you want i can find the script i was working on.
by bronyx85 at 2013-02-14 03:10:59
Thanks for your detailed help on this.
Its been a nightmare.. Could you please post me the script you have?
Many thanks 🙂
by bronyx85 at 2013-02-27 03:50:37
I need to update a list Content Type Trying in vain to get something to work.