The 90days starts again from 0, the day you come back in the country. It is automatic, no need to go anywhere.
I just went to Vietnam few week ago, and didn't di anything for 90Days or TM30 (but i'm "manage" by Chiang Mai Immigration, and could be quite different in another part of Thailand : each Immigration bureau wrks a bit as it's main officer decides).
It depends of which Immigration bureau you report to. In Chiang Mai, as far is my own experience, after you made the first TM30 registration, Immigration doesn't ask any new TM30 declaration when you leave and come back at the same place (even from a foreign country).
But in this precise case, the link I gave is NOT not PDF but a simple web page. I can open it with any of the six browsers I have on my Mac, my iPhone or my iPad. Don't see any technical problem, sorry.
As far I understand, for some reason for which Thai immigration has the secret, the new 3m bht requirement is only for new OA visa and AO year stay extensions, but OX visa keeps the same insurance requirement as before.
Bobby Howard Yes, you are stamp but in the OX regulation (at the section Other useful informations) it is clearly written : "– Foreigners must report, in person, to the immigration officer every 1 year for the examination of the qualifications and supporting documents. " You must extend the authorization of stay every year and in the case of XO you must have to prove that you did and will maintain the money reglementation of this very particular visa.