Hey Mark,

If you’re talking about YouTube or externally linked media specifically, if you inspect it – it might be controlled through the iframe class, in which case you can edit your style sheet with something like

#spMainContainer .spPostContent iframe {
    max-width:100%;
    width: value;
    height: value;
}

Entering something into the width and height will change the size of the iframe so you could use something like 640 x 480 instead, or whatever is suitable for the size of your forum / post content.

However, if you are referring to uploaded media, you can change the size in your Admin panel under Forum > Components > File Uploads.

Down the bottom on the left you have options for width / height / file types etc..

Hope this helps

Thanks

glad we could help!