I am pretty sure this has something to do with the dreaded AutoLayout. (been trying since 2days to get hang of it)
So I mastered it somewhat, but now I have problem where my UIScrollView is not scrolling fully down, pictures are much better at explaining these things
so the problem is the scrolling is happening but then again it springs back up. So I am not able to click on the signup button
Edit:
I have created a little example on github for you to look at, here. The project illustrates the answer below and uses the techniques I describe and nothing else.
Original Answer:
couple of things I would advise here.
First, I know you've been trying for a while but remove all the current constraints (painful I know but). Do this for clarity as ....
The view should be the size of the scene, it looks like you want the scrollview to be the full screen so that too needs to be the size of the scene.
e.g. if you are designing at 6Plus by default the scene size is 414x736 so the view and the scrollview it contains should also be 414x736.
Now the constraints for the scrollview are simple. It needs zero spacing to all it's edges.
You can add the content view to the scrollview in a couple of ways. The way I try to do this varies from project to project and depends mostly on how complex the scene is. If it's a really busy scene I keep the content view outside of the scrollview in interface builder so that I can work on it easily and visualize the whole of the view. Then I add the content view to the scrollview in code.
If its a simpler view You can add it inside the scrollview in interface builder. Ultimately whichever way you do it, you can lose visibility of the content view in interface builder because the contentview is larger than the scrollview and the content gets obscured. So play about and find a good way for you.
Note: if you do this proportially your life will be easier later. If you do all this with fixed heights the storyboard will break on different device sizes.
First pin the contentview
Notice the -400? Remember the content view is taller than the scrollview and we will change this immediately.
Select the bottom constraint (-400) that we have just created:
Select the drop down arrow next to the constant value:
Select Standard Value and type in 0 for the constant.
You should now have a storyboard with no broken constraints and if you build and run you should get a scrollview as desired.
Your bottomspace to superview on your content view is set to -74.0, I don't know if there is a reason you had to do that, but try setting it to -8.0. I think your scroll view is scrolling up to the 0.0 mark automatically