Hello!
First off, I would like to mention that I could not run the program using only Random.Range(blah). I had to add either System. or UnityEngine. as a prefix or the red squiggles would not leave me be. I chose UnityEngine. because using System. created a red squiggle underneath the “Range” part.
void Update()
{
int index1 = UnityEngine.Random.Range(0, level1Passwords.Length);
int index2 = UnityEngine.Random.Range(0, level2Passwords.Length);
int index3 = UnityEngine.Random.Range(0, level3Passwords.Length);
print("Level 1: " + index1);
print("Level 2: " + index2);
print("Level 3: " + index3);
}
So I had my play with Update and the test proved my code was sufficient in choosing a random number.
I wanted to see what behavior the RNG would have if I inserted the random index picker into my AssignPassword() function.
string AssignPassword()
{
password = "password";
int index;
switch (level)
{
case 1:
index = UnityEngine.Random.Range(0, level1Passwords.Length);
print("Level 1: " + level1Passwords[index]);
password = level1Passwords[index];
break;
case 2:
index = UnityEngine.Random.Range(0, level2Passwords.Length);
print("Level 2: " + level2Passwords[index]);
password = level2Passwords[index];
break;
case 3:
index = UnityEngine.Random.Range(0, level3Passwords.Length);
print("Level 3: " + level3Passwords[index]);
password = level3Passwords[index];
break;
default:
Debug.LogError("Invalid level number. <AssignPassword()>");
break;
}
return password;
}
Once I ran the code and tested the level selection and word assignment over and over, I could see that the RNG was working properly!
Have a nice day 
-GK