why u tube picture in my iPhone SE color dark

Hello banu2,

For help with adjusting the brightness on your iPhone SE, the best steps are in this helpful article: Adjust the brightness and color temperature on your iPhone or iPad

About brightness levels

iOS devices use an ambient light sensor to adjust brightness levels based on the light conditions around you. The sensor lowers brightness in dark locations and raises brightness in light locations. The auto-brightness feature is on by default.

When auto-brightness is on, you'll notice that the brightness slider on your device moves according to changing light conditions.

To turn auto-brightness on or off:

1. In the Settings app, tap Accessibility.

2. Tap Display & Text Size.

3. Scroll to Auto-Brightness and tap to turn the feature on or off.

If you think your screen brightness isn't adapting correctly, try to turn off auto-brightness and then turn it back on.

Best regards.

Your YouTube "Appearance" setting is most likely on dark. To solve this, follow the steps below.

1. Open YouTube
2. Click on the Profile icon in the top right.
3. Follow below

Settings > General > Appearance > Change to whatever theme you like

Hope this helps!