@DianeL1792
You cannot update Wi-Fi settings for Google Nest devices in the Google Home app. (For certain older cameras and doorbells, you can update the settings in the Google Nest app.)
Google Nest's instructions are below. Basically, you need to remove the Google Nest device from the Google Home app or the Google Nest app while you are still on your old Wi-Fi network, and then do factory reset.
https://support.google.com/googlenest/answer/10165378
In fact, the process is problematic enough that Google Nest's first suggestion when getting a new router/modem is to set the network name (SSID) and password on the new router/modem to the values used on the old router/modem:
https://support.google.com/googlenest/answer/9223711?hl=en&sjid=10096754356004013697-NA#zippy=%2Ctry...
