Changing from one license "suite" to another

Currently a program I'm modifying is licensed under the GPLv2 license. However, I'd like to know (and yes I know no one can offer true legal advice short of a lawyer), can I as a modifier of the code, release my version of that code under a difference license (particularly, one of the Creative Commons licenses)?

The short answer to your question is no.

In order to change the license you would need the agreement of the original licensor/copyright holder(s) of the software you have changed.

In that case, can it be upgraded to the newer version or will that require said agreement as well? In short, what can I as a modifier do with said license?

Hi,

By newer version, I assume you mean GPLv3.

Again, you cannot change the license, even to a more restrictive version eg v2->v3 without the agreement I mentioned earlier.

Is there a reason you want to change the license?

I dunno I'm generally more a fan of the Creative Commons' licenses but sadly I understand that I have to comply with those licenses already present. and I'm guessing any contributions/changes I write still have to be written under the same license?