OnePlus
Change Lock Screen Wallpaper auf OnePlus
On OnePlus phones running OxygenOS, the lock screen wallpaper is controlled separately from the home screen wallpaper. This is why changing one does not automatically change the other, and why the rotating daily wallpaper keeps reappearing on the lock screen even after you pick a new home screen image.
To set your own picture, open Settings ➔ Customization ➔ Wallpapers. Select the lock screen slot, then tap My photos or swipe left and right to browse the built-in wallpaper collection. Pick the image you want and confirm with Save.
Why this matters
The daily wallpaper feature downloads a new image automatically and applies it to the lock screen only. If you want a fixed personal photo there, you need to override this feature manually using the steps above, otherwise your selection gets replaced again after the next automatic update.
If you only want to change the home screen background and keep the daily rotation on the lock screen, skip the lock screen selection step and apply your photo to the home screen slot instead.
Some custom launchers or third-party lock screen apps can override this setting. If your new wallpaper does not appear after saving, check whether such an app is active and disable it before repeating the steps.