Here my question is how to keep password safe so that we don't forget it.
Don't try to remember all your passwords, this is impossible to do.
Instead you can use some open source password managers like KeePass and remember only master password.
Than you can use KeePass to generate and save strong password.
How to activate 2FA on the account? I have heard in various articles and youtube that enabling 2FA on account makes account much more safe and secure.
It's more important not to click on any links you receive from other members in PM.
Remember to save backup of 2FA if you are using it, KeePass can also be used for this.