Bridges are arranged in numbered order, and where they sit directly affects pitch, playing feel and string tension. It is the part of routine guzheng maintenance that most often needs adjusting.
Slacken the relevant string before moving a bridge, then tighten it gradually once the bridge is in place. Forcing a bridge along while the string is under tension can scratch the soundboard and may also damage the base of the bridge.
When setting a bridge, make sure its foot sits fully in contact with the soundboard and that the string passes smoothly through the notch. Any gap between foot and soundboard will usually show up as a buzz when you play.
If a particular bridge keeps shifting while you play, first check that it is in its numbered position, then check whether the string has enough tension. Ask your teacher to help with the adjustment if needed.
After changing strings or replacing a bridge, both pitch and feel will change. The instrument needs retuning and a period of settling before it feels normal again.