Re: What does this mean?
If the needle is in good condition and the seating surface is clean, finger tight is enough. If you use a screw driver and over tighten it, the needle (and seat) will damage.
If you cannot get your fingers onto the screw then a screwdriver is your only choice, use two fingers to operate the driver. That way you will minimize the amount of force you can apply.
It is one of those things that requires 'feel'. It is not something that can be explained with torque values.