I start my MAMP and try to connect to my MySQL server via localhost or 127.0.0.1, I tried all the possible password that I think it is correct, but
localhost
127.0.0.1
Follow those instructions and you should be fine:
https://svendeswan.wordpress.com/2016/01/26/mysql-reset-root-password-without-knowing-it-mac-mamp/
which is based on this one:
https://www.tech-otaku.com/local-server/resetting-mamp-mysql-root-user-password/