I'm having the same issue. I've tried clearing cookies (huge pain in the A) and cache.  Nothing works. It stopped doing it for a little while when I switched to 1Password, but then started asking for the code again last week after ensuring that I'm not a Robot (10x a day!). I did not change anything at all so no clue what caused it to stop recognizing my computer.  Like everyone else I have my 2-step verification turned OFF so this should not continue to happen.  QBO needs to have a "remember my computer for 30 days" option or just fix this problem.  So many issues with QBO - the only reason I'm using it is because one of my clients has it.  Thankfully my other clients use different systems. Not impressed.