Step 1: SSH into Laravel Forge
First, you will have to SSH into your Laravel Forge by using the SSH command line.
Step 2: Change to Super User
Now that you have logged in you will have to change to the superuser (You will need to have your root password to run this).
Step 3: Upgrade Composer Version
Now to update the composer you can run the self-update command.
composer self-update --2
composer self-update --1
Step 4: Check New Composer Version
Now to check the new composer version you can use the --version flag on the command line.