In line with good security practice, you can configure a password strength meter to encourage users to enter strong passwords when signing up with a password. 

Set this up in Site Settings > Security > Passwords > Password Meter - select the level of password strength you wish to enforce:

ModeEffectHow It Displays
  • Do not display the password meter
  • Allow passwords less than 8 characters to be entered
  • Display the password strength meter
  • Minimum 8 character passwords must be entered
  • Password strength tips shown
Enforce Strong
  • As above except you cannot continue unless there are upper- and lower-case characters plus a symbol
As above, but if you try to proceed a warning will appear stating what is missing.