When you input a tempo and change it, it changes the tempo to something that isn't what you inputted. For example, if you put a quarternote=80, and change it to 165 (or whatever), it will go really slow. And if you put 65(or something lower than the first one), It goes faster.
Comments
Please use the Support forum https://musescore.org/en/forum/6 to ask for help using MuseScore, not the issue tracker.
Have you checked the settings in 'Inspector'?
https://musescore.org/en/handbook/tempo#edit-tempo
Please attach a score to reproduce the problem.
Also see #78416: Tempo text oddities in score with linked parts until save/reopen. If your score has parts generated already, there is a known issue requiring a reload to hear the tempo change correctly.
Closed due to lack of response and inability to reproduce. Please report, in English, and with precise steps to reproduce, in a new thread if this still troubles you in the latest version (3.4.2).