Thanks for joining this thread, SDItax.

I appreciate you trying the troubleshooting methods mentioned by the QuickBooks Desktop Support Team. Since the issue is persisting, I recommend submitting feedback to the Product Development Team for review. This is the best way to make your request known about increasing the attachment size limit. The majority of product updates and feature releases come directly from user suggestions like yours. 

Leaving feedback can be done directly through your QuickBooks account by clicking the Help tab, then Send Feedback Online.

If you have any other questions please don't hesitate to reach back out. The Community always has your back!