CKEditor doesn't work properly on some mobile devices. So CKEditor developers decided that, when a mobile browser is detected, CKEditor should stop its initialization. That is not related to Q2A and there is no setting to enable that in Q2A.
Some official info here:
Some previous discussion on this forum
here.
Now, if you still want to make it available to your users, at your own risk, you can add this to your qa-theme.php file:
public function body_script() {
parent::body_script();
$this->output('<script>CKEDITOR.env.isCompatible = true;</script>');
}
This will override the compatibility check and make it always enabled.
