To be 100% clear I need to know which version of the timer you have, the first generation timers have to be put into pairing mode but the second generation timers are always available to pair.
Otherwise, you can do a factory reset on the timer but do not delete it from your account. To factory reset it, plug the timer in, open the swing panel then press & hold the reset button until the whole screen lights up then goes away. Then go to the app and tap on the network icon in the upper left of the app’s home screen then tap on Update WiFi and follow the steps to connect to the timer and input the new WiFi information. Once it has reconnected with the server it will download all the saved programs and settings and you’ll be back up and running.
Let us know if you need more help.