You could need to find where those buttons are located. I assume they are in a Layout that is shared between multiple page, but you know your app better than me.
They are probably action buttons, so you would just need to change these from "Open a page" to "Call a microflow" to make them call a microflow instead. In your microflow, you will probably need to have a "Show Page" action as the last action to show the page that was originally being called.
https://docs.mendix.com/refguide/button-widgets/
I hope this helps.