To change the wifi the nest cams connect to you have to factory reset them.

What you'll need:
Nest Cam + magnetic plate
Charging cable (plugged in)
QR code
Pen, paperclip, small screwdriver, etc
Phone with google home app

Remove the camera from the moutning plate and press and hold the reset
button on the back for 12 seconds.

After 12 seconds the camera will make a jingle. Keep holding the button
until the jingle ends.

Place the camera back on the magnetic mount. After the light goes off
plug in the charger.

When the camera boots up you will see a solid blue light on the front and
hear it jingle again.

In the google home app, tap the name of the camera that is offline.

Tap the settings gear in the top right of the screen

Tap "remove device" at the bottom of the page. Tap remove again on the
popup.

Tap the "+" symbol in the top left of the screen.

Tap "Set up device".

Tap "New Device".

Tap the name of the home you're adding the camera to, then press "next".

On the "what are you setting up screen, tap "camera". Then select the nest outdoor/
indoor battery.

Scan the QR code if you have it. IF not, press "continue without scanning".
(if you scan the QR code, setup is automatic)

Press "continue without scanning" and enter the setup code located at the
bottom of the camera

Once you have it typed in, press "next" and select the picture of the camera
you are installing and press "next".

Press "continue" and accept Googles terms of sercie, privacy guidlines, etc.

On the "help improve" screen, I press "no thanks". Just my personal preference.

Press next until it asks you where you are putting the camera. Select indoors
or outdoors.

The screen will say "connecting" at the top, then
it will search for wifi networks. When it shows the
list of wifi networks, select your network

Press "next" and type in your password, then
press "next" again.

The camera will make 1 final jingle when it
connects.

Select the room the camera is in, press next.

Position the camera where you want it and press "next".

Select how you will mount the camera and press
"next"

Select which surface you will install it on. I'm
selecting "already installed". Press "next".

It will ask to position the camera again. Press
"next" on this screen and the next two.

On this screen, you can choose to turn video
recording or not. I don't for this tutorial.

On the next screen you can choose to turn on the
microphone. If you want to talk to people through
the camera, turn this on.

On these following screens, it will ask to set up
home and away rules, and Nest aware. If you want
these services, go ahead and set them up.

Press "next" to skip the video on the app.

Press "done" to finish

Select your camera from the list to view it.