Hello, Pegah. Your notes are sent to relays first, then the rest of the world can read your notes at those relays. It seems your notes sometimes reach good relays, sometimes they don't... You can, however, chose to pay for a business relay that would take care for you about your notes being displayed the best possible way. Also sometimes other users can see your notes and re broadcast them to other relays also helping your notes to reach farther 😉 . Be well!