Don't have view options in finder
It can be confusing at times.

Set finder to open as icon.

Then in finder while viewing icons you will find a small slider at the bottom right of the finder window.
It looks like this:



EDIT:
To change icon size on Desktop:

Click on:
Show View options

in Finder with desktop background (close all other windows)

You will get this, 



allowing you to change the Desktop icons sizes.

Alternative method to use making sure the Desktop is the TOP window (in focus) use this method.



If none of above works for you, check the date of the "com.apple.finder.plist" in Library, and if not very recent than Delete it.