Enabling dark mode in QBO seems a helpful feature for your business, Ken.
Please know that the option to switch QBO to Dark Mode was previously available as part of the beta features offered through QuickBooks Labs. But we discontinued QuickBooks Labs, which also removed Dark Mode and QuickBooks Themes.
To have this option again, you can share your feedback with our product engineers for consideration in future updates.
Here's how:
 
- Log in to your QBO.
- Go to the Gear icon in the upper right and choose Feedback under Profile.
- Type in your recommendation in the Share your feedback field.
- Hit Next to submit your suggestion.
 
If you also want to enhance your QuickBooks layout, you can personalize your Home Dashboard and arrange the widgets according to your preferences.
If you require more assistance with handling QBO, return to this thread. We are here to ensure you receive the necessary support managing your business tasks.