Hi there,
When you activate Inherit Query from Template the Query Loop will use the main query, that includes the number of posts that are set in your Dashboard > Settings > Reading.
If you’re creating a page where you want to show just the very latest post, then don’t use the inherit query, just set the params you require.
At this time, you can’t add params with the inherit query, if thats required it will need some code. Let me know