Can I please have your full model number, baseband version, Android version, and service provider?
Are you using the stock clock app on your device?
-If yes, I would recommend force stopping and clearing the cache and data. Go to settings > apps > clock > tap on force stop > then tap on storage and clear the cache and data
Do you experience these symptoms if you test your device in safe mode:
If your phone is misbehaving, it's possible that a third-party app is causing the issue? To figure out what app is acting funny, you can use the Safe Mode feature. In Safe Mode, your phone won't run any third-party apps. This allows you to easily identity and remove the app that may be causing the problem. Give this link a try to test your device in safe mode: https://www.samsung.com/us/support/answer/ANS00062983/