Password authentication failed for user "nearbyshops"

Ok So I was trying to take a backup using [] But it was requiring password for the user nearbyshops, So I changed the password to ‘password’. Now the entire app has broken down and isn’t running. Does any one know the default password for postgres user “nearbyshops”.
I have tried everything from reinstallation of image to reinstallation of docker, etc. but nothing resets it back to its original password.