Disable the file extension change prompt
In Finder go to the "Finder" menu and select Preferences. Click on the "Advanced" tab. Either Check or Uncheck "Show warning before changing an extension" depending on the behavior you want.
Note that it is not possible to change what the default action is (EG press Enter for [respectively] "Remote" , "Don't Add" , "Keep .png"). That is baked in to macOS as a default action. This is always going to be the action that will potentially NOT make a change that could cause a potential issue.