I've got a domain that I apparently forgot to set a preferred domain for, so I just tried to do it. Webmaster Tools instead popped up a little box:

Part of the process of setting a preferred domain is to verify that you own http://www.example.com/. Please verify http://www.example.com/.

I'm running into some problems following these instructions:

1. As far as I can tell I already did verify sometime in the past. There's a TXT DNS record with the gibberish Google tells you to set for it that I couldn't have come up with myself.
2. …and nothing is telling me this information is bad.
3. So let's assume the site is somehow not actually verified. All the various methods' instructions start with "click the Manage Site button next to the site you want, and then click Verify this site." That button doesn't even exist on my screens. (It presumably goes away when you successfully verify?) Those instructions were all updated pretty recently, and the DNS one in particular just a couple weeks ago so it seems a bit unlikely they're inaccurate.
4. I am not using Apps, and won't be, so can't try out the verification through there.

Note that I also have another domain that I have not done any verification for which is showing the same behavior(no such button, being told to verify when it seems impossible etc.) so something appears to just be broken.

I already have a no-www process in place server-side, so we can skip that. I'm just trying to get the box checked off in GWT.

If I don't get any resolution, I'll eventually scrap the TXT record and see if the site gets un-verified(or whatever since it thinks it isn't), and see if I can just restart the process. It's not urgent so I'm just trying to figure out if I've gone blind to something or what. Did the button move?