I am a serious and relatively quiet for an unknown person at first, colleagues may be uncomfortable, but I think that's just a temporary problem, because I would be very well-received when some known.
I was rather serious and quiet for people who do not know, at first, a colleague may be uncomfortable, but I think that's just a temporary problem because I can be very friendly when known a while.
I am very serious and quiet for people who don"t know at first colleagues may be uncomfortable, but I think that is only a temporary problem because I"m very friendly, when known, สักพักนึง