I recently added a link to my business (www.wasp-security.com) to another forum and the link title automatically changed the description to "WASPsecurity Security With a Sting"

Not complaining but wonder how to change that to something more pertinent to Thailand as it may help with SEO.

depends on the forum. If the forum automatically took that from your site you are maybe stuck with it. If the forum allows you to edit the html you can change it.

It does seem like the text is taken from your site. If you feel you need some keywords about Thailand then that should be added to your site - in the Page title and h1 text.

That is the title of your homepage (view source, search for the title tag). If you change that to something different, you will get different results in future.