Samsung
Turn Screen Rotation On or Off auf Samsung
Screen rotation on a Samsung phone depends on a single toggle in the Quick settings panel. When it is set to Auto rotate, the display follows the physical position of the device and switches between portrait and landscape. When it is set to Portrait, the screen ignores how you hold the phone and stays fixed.
This is why some apps rotate freely while others seem frozen in one orientation. The toggle applies system-wide, but individual apps can still request a fixed orientation regardless of the setting, which explains cases where rotation works in the gallery but not in a specific game or reader app.
Turn rotation on or off
Open the Quick settings panel by swiping down from the top of the screen with two fingers. Look for the tile labeled either Portrait or Auto rotate.
If the tile shows Portrait, tap it once to switch to Auto rotate and enable rotation. If the tile shows Auto rotate, tap it to switch back to Portrait and lock the screen.
To lock the display in landscape instead of portrait, enable Auto rotate first, physically turn the phone sideways, then tap the same tile again while it is showing the horizontal layout. The screen stays in that orientation until you tap the tile again.
If the tile is missing from the quick panel, it has likely been removed from the visible row. Edit the quick settings layout to add it back before repeating the steps above.