If you want the entire course to be set as pass/fail, change the grade type of the course grade category from value to scale and choose your pass/fail scale of your choice. You can create a new scale if needed.
If you have oen or more items in the course being assessed as pass/fail and all are required to be attempted, set the aggregation method to lowest grade.
Alternatively, you could look into course completion options (not grading) - look in course settings and enable "Completion tracking". You will then see "Course completion" options under Course administration.