Bangle 2. How to set GPS Serial1 baud rate?

yes, confusing.
Anyway. after discharge, it works again with 9600. However once I switch to another frequency, GPS produces output, but does not accept input.

Bangle.setGPSPower(1,"TST");
Bangle.on("GPS-raw", function(m){print(m);});
// I see output

Serial1.println("$PCAS01,2*1E");
Serial1.setup(19200,{rx:D30, tx:D31});
// I see output

Serial1.println("$PCAS01,1*1D");
Serial1.setup(9600,{rx:D30, tx:D31});
// no output, it looks like CAS01,1 was not accepted

Serial1.setup(19200,{rx:D30, tx:D31});
// I see only output again.

What am I doing wrong again?
@fanoush, were you able to switch baud rates back and force?