how do I change the password for my router settings

You sign into your routers administrator account, and follow that specific router model's user guide for changing the password.

That would depend on the make / model of your router. The manual/user’s guide should explain that.

If you have an Apple AirPort Extreme, then Applications-> Utilities-> Airport Utility

many routers has a webserver one configure them on

apples routers had an util called airport util to handle it

sure other manufacturers have their special ways too