Hey Yellowdvl, Welcome!
Another way to change your tracker is just to click on it--and then follow the directions. But the step lots of people miss is to save it after making the change.
Your weight loss of 3 pounds in 1 week is GOOD!
Most people find that they have to keep track of their foods in some way. As Chick in the Hat mentioned, calorie counting is easy, and you can use a tracker on the computer to do that. FitDay is one that a lot of folks use, and there are many other sites--Calorie King, The Daily Plate. Each program has a big database of foods with the nutrition information, and the program enters the details for you.
Other programs use ounces of food or a points system to keep track.
The number of calories you should eat in a day depends on how old you are and your weight, and your level of activity. FitDay estimates this for you as well. Let's say that you burn 2,000 calories just in the course of a day, with activity and just bein' alive. To lose a pound a week, you would not eat over 1,500 calories per day, which would mean a deficit of 500. A pound is 3,500 cals, so 7 x 500 = 3,500. A weight loss of 1-2 pounds a week, average, is considered healthy--many sources say folks shouldn't go below 1,200 for extended periods of time, except under a doctor's care.
Getting some exercise is also a good idea--it raises the calories you burn, but more important, it improves your muscle tone, and muscle is good at burning fat. It doesn't have to be anything more than walking to start.
So maybe that gives you some ideas...?