UBB.threads v7.6+ is responsive/mobile capable out of the box; as long as structural site elements do not stretch the viewable area past a mobile capable view (such as huge banners or a large logo which are not placed a a responsive way).
I invite you to load the UBBCentral
forums on your mobile device.
It is important to note that not all styles are responsive or have padding wide enough for Google to not warn about touch points being too close.
In the case of your forums, your logo and page navigation are in a table together, so they're sharing the space 50/50; for mobile users however this is quite a bit of content to display on a tiny screen.
If you set your logo on one row, then your navigation on another row, and set the image to have a style="max-width: 475px;" vs width="475px" it should allow smaller browsers to load a smaller version of the image.