Images issue

I noticed a User was uploading screenshots of their game in a thread in my forum yet as you can see in this screenshot only half the image comes out. How can I fix it so it shows the full image now and for future times? 

http://prntscr.com/5n5qop

What happens when you refresh the page?

Nothing. It stays the same. The user hid the images in a spoiler and when you click it only half the image appears Like if the Image is too big or something.

Is it not loading or is just cut off?

Just cut off. Loads fine.

If I recall correctly, on phpbb3 the overflow for posts is hidden, so that causes content to be clipped that overflows. You can enable image resizing to resize images, that would be your best choice.
Administration Panel > General > Messages and e-mails > Configuration > Images resize

If you don't want that, you can also use some CSS to resize the images instead.

I would go with the CSS code, but I don't know it. Is it posted somewhere here in the Support Forum?

Display > Colors > CSS stylesheet

Code:

.post .postbody .content img {
  max-width:250px;
  max-height:250px;
  transition:500ms;
}

Set the maximum dimensions to what you want. The transition is if you want a smooth transition for events. For example, increase the max dimensions on hover so the image becomes larger :

Code:

.post .postbody .content img:hover {
  max-width:500px;
  max-height:500px;
}

Thank you very much!