Need help changing WAN from 5 GHz to 2.4 GHz

Hello Noob here,
Installed openwrt long time back and never touched again, recently upgraded openwrt software to latest version and tried to play a bit with configuration and everything messed up.

My Wan appears to be on 5 GHz and many devices cannot identity same, need help to setup same SSID to 2.4 ghz and 5 ghz both
(or change 5 ghz to 2.4 ghz).
Not sure why wifi SSID is not appearing on each and every device at home.

I dont know how to edit config files, request to direct me from openwrt User interface.

Go to Network -> Wireless and make sure both your radios are setup correctly. Then click the "Enable" button for each radio you want to start. With both radios started and working on 2.4ghz and 5ghz then all your devices should be able to connect.