A while ago, I created an (embedded media) 3rd party video field for my blog and I set up the preview size (not the thumbnail) to be 200 x 150.

Later on I deleted that field because it doesn't look good with my them.

Now, I re-themed my site and tried to embed some youtube videos into the blogs (without adding additional field to the blog, just embedded the youtube link straight into the blog content).

But the preview size remains! So instead of getting the default preview size 425x350 on the blog, I get the 200x150 size that I set up previously.

Is there a way to "reset" that previous size to be 425x350? It seems like the field is deleted off the blog but not its setting. It's been a while so I couldn't recall the field machine name.