"Calling" ring tone change in Verizon Messenger+ on Tablet?

[NickinVA]

Running Verizon Messenger+ on my Samsung Tab S3. App is surprisingly good and highly configurable. One thing I can't figure out is how to change the ringtone (or mute it) when a call comes in. I can easily find the text message tone and change that, but when a call comes in, the super annoying stock Verizon ring tone comes blaring out at 1000 dB.

I see the switch to turn Calling off-on, but no settings that I can find specific to that function. Grateful for any help!