That's correct, as you mentioned you need to be 18 to have a Shopify store as per the Shopify Terms of Service. What you would need to do is have some who is over the age of 18 such as a parent or gaurdian who can be the Account Owner (AO). Once they are the AO they can verify their details and attach their bank details. Once that is set up correctly the payout will be issued to their account and you can get the money.
To change the account owner you can see the help guide Shopify has for this here. Let me know if you have any other questions about Shopify or getting set up!
In the case you can't find anyone 18 or over to become the AO then you won't be able to verify the account, recieve any payouts or legally run the store. This could alert the Risk assessment team who could close the store as a consequence.
The $76 won't go anywhere. It will stay put in your store until it has a verified owner when it will be paid out. It can't be paid out until the store is verified for legal reasons.
Section B, part 3 of the Shopify Payments Terms of Service goes into more detail about this.