For people looking for an answer to this, I'll post the best workaround solution that I found reading through this thread:

Clicking 'Add Subtotal' has prevented the lines on my invoices from auto-arranging when I go to send my invoices to customers. If my invoice is a confusing mess due to lines shuffling around it makes my customer question if I should be performing detail oriented work for them. Hope the software engineers can simply remove this auto-arrange flaw soon, was a frustrating evening until I found this thread.

Also, looks like this forum autosaves my work quite frequently, wish QBO would do that as I'm at about an hour of accumulated time rebuilding lost invoices/estimates that were lost due to various circumstances that autosave would have prevented.