Temperature display suddenly moved up by 1/4

Moin The temperature indicator has recently moved up by a quarter. If I switch on the ignition in cold engine, the pointer is already on the 1/4 bar. The fan is now only turning on in the red area, instead of at about 3/4 of the indicator. What can it be? Is it really only the temperature indicator that spins – or maybe something else? Cooling water is enough in it, I also checked the thermostat. Hot water tipped over it and it runs out (and I am grateful for every advice. LG Michael