CMS Attachments Manager question

[محروم.كوم]

Hi all,
I'm attaching images to articles via the paperclip/manage attachments, and clicking 'add images' and uploading from my pc. I have my image max settings in my AdminCP Attachments Manager set to:

max size 20000 / max width 800 / max height 450

but my article images are mostly uploading into the attach manager window as 20kb, instead of 100-200kb and the pop-up image is around 400-500px wide, instead of 800px wide.
It has however worked for a couple of images [60kb/800x450] but I don't know what I'm doing differently.

when I click on the blue question mark in the manage attachments 'add images' sub-window, it tells me that the max size is 19.5kb, while the ratio is still 800x450.
I've checked my usergroup attachment permissions, re-checked my attachments manager. I can't find where else to change this.
Is there anywhere else I should be checking? A pop-ups manager?
Thanks for any help you can give.
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