Welcome to the forums! You can possibly send the following the commands to change the baud rate:
4800/8/N/1 - $PSRF100,1,4800,8,1,0*0E
9600/8/N/1 - $PSRF100,1,9600,8,1,0*0D
19200/8/N/1 - $PSRF100,1,19200,8,1,0*38
38400/8/N/1 - $PSRF100,1,38400,8,1,0*3D
Please keep in mind that these changes are temporary or leaving the BU-353 unplugged from power for 72 hours would reset the device to default.