PenciDesign replied
Hi,
1/ When you insert images to your editor, please select the size for your images is "Full Size" - check this image
2/ Because you're using Single Posts Style 2. Please go to Customize > Single Posts Options > and un-check on "Enable Single Posts Style 2"
3/ Please ask your hosting provider about this issue. The hosting limited this upload.
Best Regards,
PenciDesign