Oppo
Set Default App Storage to SD Card auf Oppo
Internal storage on Oppo phones fills up quickly once photos, cache and app data accumulate, even with a large SD card installed. ColorOS does not let you move installed apps onto the memory card, but it does let you change where new app data gets saved.
Open Settings ➔ Storage ➔ SD card and turn on the option that sets the memory card as the default storage location. Any app that supports external storage saves new files, downloads and cached data there instead of on internal storage from that point on.
Why this only affects some apps
Not every app respects this setting. Apps that store data in a protected internal container, such as many banking or messaging apps, keep everything on internal storage regardless of what you choose in this menu.
Switching the option off later does not move files back automatically; existing data on the SD card stays where it is, and only new data follows the changed setting. Removing the SD card while apps are actively writing to it can cause errors, so eject it safely from the same storage menu first.