Is there any better way to program automation without it jumping where ever it likes?

As the title says... I just spent an hour of my time to enter 2 same numbers to the nods of the volume control. I want a part to start at -3.2 and end at 3.2. Only 2 nods. But it continues moving up, goes -3.2, -3.3, -3.4, -3.5... I can not set the 2nd nod to -3.2. It would either do -2.8 or -3.5. I use mouse to move the green line up and down and it jumps in large increments. It also shows 2 numbers at the same time and it is hard to tell what I am looking at. But the bottom line is- it should not take an hour to enter 2 numbers. What if I need to make 20 edits on one vocal track? It would take 20 hours of work? By the way- the 2nd nod is still at -3.5, not -3.2. I can not compare it to other DAW- I am sure there other issues, but this is frustrating. My hand hurts from trying to hold a mouse and move it microscopic increments. Why -2.8 or -3.5 on 2nd nod, while 1st nod is perfectly fine with -3.2? There got to be a way to simply type in the number without dragging the green line up and down. How do you enter automation? Thank you.

Thanks!
I right clicked it like 25 times in the past and saw delete nod, replace nod- I did not think it would be under the  "property". Should of say, "Level". Ok- moving forward. Thanks again.

Another way of setting two nodes adjacent to each other to exactly the same setting is to use vertical snap. Select the node or nodes you want to adjust, hold the ctrl key down and drag up or down as required. As you approach the level of the previous node you'll see that highlight and the next node will snap to the previous one.
 
Note that if the selected nodes are at different levels the differences are maintained. To snap them all to the same level you need to do them individually. 
 
You can also snap to the previous flat section using this method.