Hi, welcome to the forums!
First of all, FICO can't (and doesn't) change scores. The scores are created at the CRA (credit bureau) site, using the FICO scoring formulas. The formulas just crunch the contents of your reports to create the scores. I'm reasonably sure that there isn't a negative scoring factor for cancelling Score Watch. 
You have three FICO scores, one from each bureau. Each bureau has its own scoring formula, slightly different from the others, because the formulas are created off the older records from each bureau. So even when my adult kids were just getting started in credit land, and each kid had identical reports for all three bureaus, they still had different scores. Also, most of us have slightly different info on each report, so that increases the divergence in scores.
You can't buy your Experian FICO score, as of February 13, 2009. 
They'd rather sell you their FAKO's.
Here's a great start to help you out: Son of Credit Scoring 101. Also, check the link for Frequently Requested Threads. There's a lot of good stuff in there as well.
Hi dee-rock! Welcome to the oft confusing world of credit scoring! 
A great resource for getting a solid foundation of knowledge is Understanding your FICO® score.
@dee-rock wrote:in seeming contradiction to my payment history, my score went from 702 down to 668 (Both acquired from this site).
Huh??? I raised my score to 680 and then secured a car loan and have been paying off my student loan regularly which raised it to 702. It stayed there for a year and at almost exactly the year mark for time repayments on my car loan, my score went down and drastically so?
That doesn't make sense to me.
I have a number of negative marks but those are quite in the past and were already figured into my 702 score. I had expected to log in and see that the score was actually above 702.
I also have a mortgage and that company doesn't automatically report to any agency. So I have a year history of timely payments with them as well. I don't use credit cards.
The drop also coincides with my cancellation of my initial myFICO subscription.
Call me jaded, but have more than a tiny suspicion that these score companies generate business and income by having us run around in a panic and deciding to buy their products and services in exasperated states. This is absolute nonsense that my score went down. It makes zero sense.
Anybody know what might have happened and how I can have it move back to and above the 702 score?
Confused!
Your credit scores are dynamic-- changing as often as the ever-changing (even if only aging) information in your consumer credit reports. Further, your consumer credit reports from Equifax, Transunion, and Experian (we can no longer purchases scores for Experian) are not always identical. One of the first things you'll learn is that your scores are derived from information found in your consumer credit reports. For example, your nationality, your race, your gender, your marital status, your income, and whether or not you purchase products/services from myFICO do not, in any way, factor into your score. Each of the 'Big 3' credit reporting agencies use a different version of the FICO product-- different information & different versions = different scores.
Another interesting point, that always manages to get us all in an uproar, is the existence of the ever elusive "scoring buckets". Our FICO scores weigh risk based on the specific information in our reports at any given time, but we also get 'bucketed'/compared with others who have similar credit profiles to further fine-tune *risk*, and our performance weighed in that regard too. As changes (remember, a credit report & score is dynamic) occur, we may get dumped into different buckets, and that may impact our scores.
Have your recently pulled all three of your credit reports directly from TU, EQ & EX to see if there have been any significant changes to your reports?
