Ask HN: How to efficiently update passwords for a 36+ accounts

My colleague sitting next to me was stuck today with the task of updating passwords on all employee accounts at 3rd party websites that we use (around 3 main sites that we use). Its going to take him just about about an entire day's work to change the passwords for each employee at each of the 3rd party sites.

We have passwords changed either every quarter, or when an employee leaves the company, whichever comes first.

Is there a faster, more simple way to do this that we have overlooked?