Broken images and posts are odd

[MisterW]

I have installed fresh copy of forums and installed 2 themes but on both themes images are broken because they are looking for .png images but the image files are .gif

also when posts are in classic mode it looks weird 

http://prnt.sc/dyjlcj

[Livewire]

Which theme are you using?
Also if postbit shows like that then the theme is bugged and unstable, I've been through this before try using Horizontal postbit if that doesn't work then I'm confident that theres something wrong with the theme.

[NickGHQ]

Can you post your forum URL so we can have a look to see what's causing this?

[MisterW]

I got fed up with it so reverted back to MyBB 1.6.11 and it's fine now.

[Ben]

We recommend that you use the latest version of MyBB due to the security fixes. We no longer support 1.6 and it will not receive security fixes so your site is vulnerable to the known security issues for 1.6.