Not sure how but the urls to all my images are wrong

http://www.mysite/forums/http://www.mysite.com/forums/screenshots/monthly_2015_09/2015-09-25_09.50.29.png.76cf6624646aff77cb0f4867e1e3c5eb.png

Is there anything under your Custom URL in ACP -> System -> Files -> Storage Settings -> Configuration ? If it's disabled, you may need to enable it to see.

No that seems ok, just not sure why the urls have doubled up, configuration file? 

Just realised this seems to be downloads, screenshots

I had the same issue. to get up and running I went to:

Admin>System>Files>Storage Settings>Configurations

Then edit each configuration

Select "Use Custom URL"

then, without the http:// add the full url to the uploads folder with no trailing slash, then save.

It should then work ok.