Changing Greeting on Mobile App

Hi FGE,

You will need to record your voicemail greeting through the web portal:

https://zoom.us/pbx/page/telephone/myZoomTelephony#/my-cloud-phone/settings

Login and scroll down to the Business Hours section where you’ll see Default under Greeting and Menu. Tap the Audio Library to the right of that to record your new greeting. 

Here is a link to Zoom Support page that gives more details:

https://support.zoom.us/hc/en-us/articles/360028212652-Customizing-audio-greetings-and-hold-music

I hope that helps!