How to change folder icon?

My problem is:
I have downloaded these icons that have the theme of Windows 8.
I'm changing a lot of system file icons around on my computer using the program "Default Program" it's great and all, but it doesn't support changing folder icons. I have to do it manually.

I've used two of Brinks tutorials how to change default closed folder icons and default open folder icons by using Regedit. Now I have one problem. I can't find a tutorial to change the folders icons that have the files and or pictures sticking out of them. You will see in the photo I have attached to this thread.

Thank you in advance! (:

At the risk of appearing incredibly sarcastic:

Let me google that for you

Don't even. I have been using Google on this for the last hour. I haven't made any progress. It says if -right click a folder -> properties -> customize -> change icon- that it will change them all. Well it doesn't. It changes that one in particular.

Edit: I've changed the empty folder icons and open and closed left navigational pane folders using Regedit. I just don't know how to change the ones with the thumbnail previews sticking out with out individually doing every single one.

My apologies, didn't take the time to verify the links from my own link but others have commented on them saying it doesn't work, and I just tested it myself.

A brief caution, the link provided by sk0t0s will work, but will change all folders globally.

I tried sk0t0s option. It did not work for icons a bigger size. I have to lower the size for them to take action. I have figured out why. Earlier, I remember the icon I used for that is not the size recommended, which was 256x256. It is a lower size and that's why when I zoom in, it does not take effect. My apologies. Thank you for your time.

Error: I still get regular folder icons while zoomed in more than "small icons" in the "change your view" options.
Is there away where I can just disable thumbnails from sticking out of my folders? Just change the thumbnail folder icon to like a blank folder (nothing in it) icon all at once?

CosmicPoptart, what happens if you right-click on the folder, select Properties > Customize > Change Icon...?

Can you not change the folder icons this way?

I have over one-hundred folders that appear with folders that have icons sticking out of them. That means I would have to do that to each individual one at a time.

I understand. IMHO, I really do not know of another way of dealing with the situation provided that the "Default program" method doesn't work for folders displaying their contents.