The three stars lined up in the middle stay in line throughout the night. You can check this by holding up a ruler or straight edge at arms length and lining it up with two of the three stars. So the positions of these stars compared to one another do not change. After an hour or so watching the stars, and keeping track of some easily recognized patterns like Orion's belt, we begin to notice that while the patterns persist, the whole sky appears to move. Stars high in the sky appear to move from east to west, just as the sun appears to move during the day.
New stars rise slowly over the eastern horizon, while stars in the west slowly go below the horizon.
All the stars in the entire sky appear to move together, so the patterns are preserved, but are seen in different parts of the sky at different times. However, if you look to the north, not all stars move from east to west. Stars high above the northern horizon move from east to west, just like the stars overhead and to the south.