My custom settings with the Osmo action 1 are always set to  4k/30 but videos have been recorded in slow motion 1080/8x a few days ago. I did not change settings but relied on Custom settings and locked the screen.

Is it possible to switch back the slow mo videos to normal speed? And why is this software error? I have not used the action cam for one year but yesterday and a few days before it has recorded in slow motion.
Please check this and fix the software error. Mybe there has been an firmware update lately that has created this software error. I don't know...

Hi there. Thank you for reaching out and we do apologize for the trouble. You may set the shooting mode before you shoot a video by tapping the bottom left of the screen and then selecting "Video". You may swipe up to set the resolution and frames. If you wish to return the unit to its factory settings, you may go to Settings> Factory Reset. Thank you.

you use an editor to  adjust speed, if hte sound is off it will be off. but if you said 1 year of no use you can say  it can be a user error but we would not know I suggest  checking your settings before shooting we all make mistakes