1. Last summer, my family and I visited to my grandmother’s house where is in Samutsongkram on Songkran Festival. – visited + place
2. All of our bodies were cover by powder, and we wet, but we felt very fun and happy. – check passive voice (were cover)
3. After that, we went to pay respects to the Buddha images, monks, and then to our elders by pouring water which had flowers and Thai perfumes on their hands. – respect is uncountable noun ka.