Should I change my WiFi password?
Similarly, should you change the password on your router?
Knowing the administrative password, if you've never changed it, that software can then reconfigure your router to disable many of its firewall characteristics and allow more serious malware to infect your system. "So you should change your router's password at least once."
Correspondingly, what happens if you change WiFi password?
If the pre-shared key for your WiFi SSID (it's not a password) has been changed, then all of your devices using the prior key won't be able to connect and will have been disconnected when the key changed.
Check your router's default password, usually printed on a sticker on the router. In Windows, head to Network and Sharing Center, click on your Wi-Fi network, and head to Wireless Properties > Security to see your Network Security Key. On a Mac, open Keychain Access and search for your Wi-Fi network name.