Oppo
Set Default Keyboard auf Oppo
On Oppo phones running ColorOS, installing a keyboard app only adds it to the list of available input methods. It does not automatically replace the keyboard your phone uses when you tap a text field.
That switch has to happen manually, and it is a separate step from granting the keyboard permission to run in the background.
To set a new default keyboard, go to Settings ➔ Additional settings ➔ Keyboard & input method ➔ Current keyboard, then choose your installed keyboard as the Default keyboard.
Once confirmed, that keyboard opens automatically system-wide, in messaging apps, browsers, and forms alike.
If several keyboards are installed, the same Current keyboard menu lets you switch back at any time without reinstalling anything.
This fix only applies if the keyboard app is already installed and enabled. If it is missing from the Current keyboard list, the app itself needs to be activated first before it can be set as default.
Switching the default keyboard does not delete Gboard or any other input method. It only changes which one launches by default, so you can revert whenever needed.