James Do

do you have any sample code?

these scrolling view reuse Views rather than continuing to create a new one for every item in the list (or grid)
Therefore if your device is able to fit 15 items on the screen, you will only be asked to create 15 views. If you scroll up so that the top row disappears, those Views will be reused on the bottom row rather than requiring new Views to be created.

Coming back to your code, it should now be obvious that you set the checked state when the View is created, but not when it is reused.
Rather than relying on the View to maintain the checked state you should have a custom object associated with the current view and update the custom object when the check state changes.