Can I Use the Same Password Everywhere?
It is strongly recommended NOT to use the same password on multiple platforms as it greatly increases the risk of your accounts being compromised.
If the same password is used and one of your accounts is compromised then all of your other accounts will be vulnerable to attack. Hackers will generally take the known login name and password and run this against hundreds of known platforms and the chances are very high they will find a match.
It is highly recommended to use a different password for each platform you log into. If you log into many platforms and find it difficult to remember your passwords you can use a Password Manager to securely store these. You should also use Multi Factor Authentication wherever possible.
You can check if your email has ever been compromised in a data breach via this website: https://haveibeenpwned.com/