I would use different ones ! If someone hijacks your password , that person can get into everything you have on your computer ! I keep a book just for user names and passwords ! Safest way to go . I keep it in my safe for when I can't remember one . Stay safe and mix them up !
You CAN use the same one. But that makes it easier for not just you ... but anyone trying to get your password. Because they only have to find one, rather than a different one for each site.
Personally, I use a generic password for sites that I don't care if someone discovers the password to. And an individual password for each site that I really want to protect. Then I keep a list of those passwords in an encrypted file, which of course requires it's own password.
Most folk use a limited number of passwords - even "password" - but that leaves them vulnerable to hackers. If someone evil gets your passwords, they can steal your identity, all your savings and your credit worthiness in a week!!! And any passwords you DO adopt - make them a mixture of letters and numbers to confound the hackers' searches. Single words are EASY MEAT to a determined thief!!!