WPA is not considered secure

Hi,

When i go into my iphones wifi settings, my wifi displays this message.

WPA is not considered secure.

If this is your WI-FI Network, configure the router to use WPA2 Personal (AES) security type.

i have gone on to my pc on changed my wifi security to WPA2, but then i cant log on to my wifi and when i search for available networks, my wifi is not listed.

Eventually i did find my wifi, but when i connected to it again it had reverted back to the old settings.