Positioning Vandersteens

I purchased a pair of Vandersteen 1ci in July.

Those familiar with this brand know about the sweet spot.

I find my speakers sound better - much better - when I stand up.

Any suggestions as to how to move that sweet spot down to seated level?
Tilt the back of the speakers up
I have owned the 2c and 3a. You should tilt them back. You can place something like a book and place it under the front until they sound right. Take a look at the owners manual and you will get a better explanation of correct placement!
Thanks yogiboy zavato

I have read the manual and my speakers are on Vandersteen stands that tilt them back.

Raising  the front would move the sweetspot further up. I need to raise the back of the speakers, which didn't occur to me. 
Why not take them off the stands as a first try? 
Or lower the front, it might be easier depending on how the stands work. Worst case, you could always consider a higher seat. A pillow or two would let you test that theory before wasting any money. Cheers,
Jimspov, not sure if you bought new or used, but the manual gives a detailed procedure for setting the speakers up.  If you don't have the manual the Vandersteen website has one.  Assuming they are new, before making sound judgements let the speakers get at least 100 hours on them.  The other thing not stated is what effect does standing up give?  More high frequencies or less? If you like more high frequencies then the tilt needs to be less towards the rear.  If you like less high frequencies then the tilt needs to be more towards the rear, but be careful not to tilt too much!  Getting less high frequencies, though, may be an indication of something else not quite right, but that is too hard to elaborate on.
I would suggest a call to Vandersteen. Richard answers questions promptly and will give you the best answer. 
As Pmotz said your situation is hard to diagnose without more information-like room size, speaker position, other components.
I own 3a sigs, so I can't speak for the 1ci's, but knowing Vandersteen, I don't think you should hear better sound reproduction when higher up- Unless you are sitting on the floor.
Thanks for the responses all.

I have sent an e-mail to Richard. I have found in the past he is very responsive.

I purchased the speakers new in July and have been through the manual. My problem is the opposite of what I would expect.

By better sound I mean fuller. I hear much more detail, especially in the low end. It is actually quite incredible what I do hear. I want that sound!
I owned the 5A, and could not get used to the vertically-restricted sweet spot. I played extensively with tilt and toe-in, but the benefits were minimal. In my room the sweetspot was quite low, and  the speakers sounded best when I sat on a floor cushion. Otherwise, they just sounded dead.
Ok, now it makes more sense.  If you are hearing better low end you are probably experiencing a "valley" in the response at your normal position and probably a close to flat response in the upright position.  I would suggest getting a test CD with distinct frequencies on it then put low frequency tracks on repeat and move around your listening position and even the whole room.  You may be amazed at how much variation there will be in volume.  This is the heart of why so many people say the room is the most important component.  Sometimes you get lucky, other times it's a chore to get a room sounding good.  Positioning the speakers is the first step, but more may be necessary.  
I concur, Pmotz.
Knowing Richard, he will sort this out for the OP.
A test CD( or the Vandertones) and a cheap Radio Shack soundmeter should help locate the problem.