Greetings and welcome to planDisney, Wei!
Wei, this is a pretty common mistake, and one that I've almost made myself, so I understand how it happened. The switch from child to adult
Disneyland Theme Park Ticket must be made in person at the Disneyland Resort Main Entrance Ticket booth. When you purchased the tickets you were prompted to select a park to make a theme park reservation. You will want to keep those reservations so they are available for your visit and can transfer to your updated tickets. Once you arrive at the
Disneyland Resort, a Cast Member at the ticket booth can help you change from child to adult tickets.
Before your visit, I've got a couple of tips for you to make the most of your vacation. First, I suggest downloading the
Disneyland Mobile App to manage your visit. You can load your park tickets, mobile order food, and check important wait times during your park visit. The second tip is to check out the
Disney Parks Blog to see what seasonal offerings and specialty food items will be available during your trip. Reading the blog always helps me get excited for my Disney day!
I hope this information helps, Wei. Please bring us any more questions that you may have!
Happy planning,
Melissa