The playback button won't work after I spend so much time in the program. I restart it and it works, but if I don't it won't playback what I've written.
See:
...go into your soundcard configuration from Control Panel and ensure that the "Allow applications to take exclusive control of this device" in the Advanced tab of both Playback and Recording is unticked... https://musescore.org/en/node/96811
Also say what OS you are on - we have had a few report of people having problems on macOS specifically. And then try to provide the information requested here:
Comments
See:
...go into your soundcard configuration from Control Panel and ensure that the "Allow applications to take exclusive control of this device" in the Advanced tab of both Playback and Recording is unticked...
https://musescore.org/en/node/96811
Also say what OS you are on - we have had a few report of people having problems on macOS specifically. And then try to provide the information requested here:
https://musescore.org/en/node/234811#comment-763211
reopen if you can supply more infos