For this part, when changing the input type, disconnecting all the downstream noodles, then reconnecting in the order of processing will “reset” the workflow metadata. I’m not sure if that was what you did. If not yet, try that first. It solves many workflow-runtime issues.
If still a problem after reconnecting the noodles and trying a rerun, would you please post back a screenshot of the setting you want to use on the tool form? The one you want translated into the workflow? And maybe the section of that same tool form within your workflow (the side panel)? Sort of what you posted originally. These visually provide a lot of useful information 
I don’t think this tool “pools” samples but let’s make sure.