If you use the default Calendar app on your iPhone or iPad, there's probably been a time or two that plans change and you need to change the time of a meeting or appointment. While you can always edit the event and manually change the time, the Calendar app does give you another way that's actually a lot faster.
Launch the Calendar app from the Home screen of your iPhone or iPad.
Along the bottom, select the Day option and find the day of the appointment that you'd like to change.
When you've found the event or appointment you want to move, simply tap and hold on it.
You'll now notice anchors that come up. You can now drag it up and down to change the time on that given day or left and right to move it to a different day altogether.
Once you're done moving it, just tap anywhere else on the screen and the event will be moved to where you placed it.