You are spot on. If the definition of "hours per day" is 7 when you enter a one day duration task, Project schedules it for 7 working hours. If you link that task F to S and assign resources who work 8 hours per day, they will start the successor task at the end of the first day.

My question to you is - do you know how many hours of work is involved in the tasks? You can certainly change the definition from 7 to 8 - but it will still keep the original work - duration values will recalculation (for example from 1 day to .875 days). I'd re- visit the work values (split screen with Task Form in the lower pane). Change the work values (after correcting the hours per day) and let Project recalculate the durations.