how to set torque wrench?

[Hammermechanicman]

Take your pick. Not certified for NASA but they are all good enough for lawn mowers.
To quote Taryl. "It ain't the space shuttle."

 

[Katie202]

The ones that were left wound up drifted significantly in accuracy over time.

 

[GrumpyCat]

The ones that were left wound up drifted significantly in accuracy over time.

A split-beam torque wrench will not drift if left set. No more than the bending beam Craftsman pictured.

 

[sgkent]

Split beam are too expensive for most diy mechanics. Common but not that common. Clickers are most common except small inch pounds.