If you got a new phone, or for whatever reason need to switch the device you're using, just follow these steps (it must be done from desktop, not mobile):
Login to web.kisi.io
Click on My Account on the top right-hand corner
Delete your old phone from the list of devices by clicking on the trash can icon
Now log into Kisi on your new phone, this will be your new primary device. You should be good to go!