Can someone tell me how you can have a quality score of 7/10 one day and the next day it drops to 3/10 and it says poor quality for landing page. Nothing was changed on the page from one day to the next.
The system has new information. Your initial QS is based on information it has at the time. It checked your page later and re-adjusted your QS based on this new information. Note that QS normally changes all the time anyway. See Adwords FAQ for more. You say it's because of poor quality landing page and your QS is 3. QS in my experience drops to 1 for poor LP quality and the main reason is for having a bridge page as per the Adwords guidelines and policies.