My home network says Low Security. I cannot change it. I called my ISP and they said not to worry. Wrong security is their problem. Can you help?

See the following Apple articles:

Recommended settings for Wi-Fi routers and access points

Recommended settings for Wi-Fi routers and access points - Apple Support

If you need help with your Wi‑Fi password

If you need help with your Wi‑Fi password - Apple Support

It probably said Weak Security?

Perhaps this link of recommended settings will help

Recommended settings for Wi-Fi routers and access points - Apple Support

It depends on if you live in an apartment building with people who are likely and able to hack your Router wirelessly.

It is a low risk but if your router cannot be upgraded to use WPA2/3 security then a replacement router is the only answer.

Me, I'm not worried about mine.