The Password Strength option (Memberium > Settings > Logins) allows you to set what type of passwords Memberium will generate when you have Memberium create a password using an HTTP POST.
- Simple lowercase passwords will consist of only lowercase letters
- Uppercase Consonants will add those in addition to the lowercase letters
- Uppercase Vowels will generate passwords that consist of lowercase and uppercase letters
- Numbers will add numbers to the lower and uppercase letters
- Symbols will generate passwords with lowercase, uppercase, numbers, and symbols.
As you can see from the description above, each option is in addition to the options with a lower level. If you choose Level 4 then you get everything.
If you want to control the length of the generated passwords, that can be done with the Minimum Password Length setting right above this one.