using the fm radio app, the sound is not acceptable for speaker setting and the radio stops when i browse the internet (with micrB)

is this normal or i'm the only one?

Are you unsigned the FM transmitter? If that is what you are talking about I have noticed that there is only like two options for volume. On and off. You can test this by using and turning the volume all way up and down. You will notice that it only varies at the low extreme.