What do you do when WiFi says unsecured ?

It likely means your router is using outdated, and long ago cracked Wi-Fi security settings. Namely, WEP and the original version of WPA.

Go into your router's settings page via your web browser. Look for the Wi-Fi settings. Do not choose anything that includes WEP or the original WPA. At minimum, it should using WPA2 (TKIP).

If there is no security choice that doesn't exclude WEP or the original WPA, then the modem is very old and should be replaced immediately.

Also, some public Wi-Fi hot spots have security turned off. You do not have control over that. Your choice is to use them, as-is, or not.

Wi-Fi security only helps to protect the last few feet between a client (like a phone) and a Wi-Fi access point/router. It does not protect your data once that data travels out onto the Internet. When you visit a https site (as opposed to a http one), there is a separate layer of security to try to keep anyone from eavesdropping on the content of the traffic.