Try the following steps:
Step 1: SSH into your EC2 instance
Step 2: Run the following block of commands to change the timezone
Note: This particular block of commands sets the timezone to Australia/Adelaide. You can choose your own timezone and replace it with Australia/Adelaide in the following block of commands.
$ echo "Australia/Adelaide" | sudo tee /etc/timezone
$ sudo dpkg-reconfigure --frontend noninteractive tzdata
Current default time zone: 'Australia/Adelaide'
Local time is now: Thu July 8 21:19:24 CST 2019.
Universal Time is now: Thu July 8 11:49:24 UTC 2019.