Use seven different passwords.
You need to start getting used to the idea of using many different, yet secure passwords, for different services or accounts. Reusing passwords is a potential problem that will come back at you somewhere in the future.
"Remembering seven secure passwords, however, is a very difficult task." This is the answer I'd expect. As such, let me give you a good password creating strategy.
The strategy consists of choosing one combination of words and one rule-set. With these, you will derive all the passwords you need for your machine depending on the context (where a context may be "root", "user", "backup", "bios", etc.). Let's say we choose the word combination "HorseStaple" and the following rulset to construct a password:
1) Take the 2nd letter of the context and use it as the First letter.
2) Add a "!" char.
3) Add the word combination replacing all "e"s with the third letter of the context.
4) Add the first letter of the context Capitalized.
This sounds complicated, but look at these context - password pairs:
"boot" - o!HorsoStaploB
"user" - s!HorseStapleU
"backup" - a!HorscStaplcB
You are free to simplify or make the rule-set as complicated as you want. This also works for passwords you use in other sites:
"gmail" - m!HorsaStaplaG
"facebook" - a!HorsaStaplaF