vBulletin Forum (4.1.5) - Private Forum and Change Attachment Settings

I would like to find someone very good at vBulletin. I have hired others to fix the attachment issue (three times) and yet they still persist. So I would like someone who knows vBulletin (ver 4) well go in and change the settings so that the attachments can be viewed much larger when they are clicked on. Right now, when users post .jpg, .gif, .png files, they are very small and difficult to see (even when users click on the image). I would like them to increase in size when users click on them, so they are easier to see. Images are critical to this forum. Also, I would like to setup a private (paid) forum in addition to this (currently) free forum.