How do you change your remaining calories?

What do you mean? Can you be a little more specific?

If you are under calories, eat more, if you are over calories, exercise

The only way to change your "remaining" calories is to eat if you are under or exercise if you are over. Although, looking at your food diary you should really be more concerned about what your eating as opposed to how many calories you are over/under. Unless you just aren't completing your journal but you eat very little. Yesterday you were over, though I think those 2 slices of pizza are WAY off on their calorie count because a regular slice of cheese pizza is about 300 cals, I don't see how a slice of veggie pizza is 480 calories. Anyway, most days you are under and you really aren't eating enough and when you do it's not really anything nutritional and that's not going to help you to keep weight off or tone up.

Also, are you 14 or 21? I'm a little concerned for you because the height/weight that you have posted in your profile puts you at a healthy weight. Your UGW of 87 lbs (even at 4'11") puts you significantly underweight. The LOWEST you can go and still be considered "healthy" is 91.6. After reviewing your diary and seeing that you are trying to get to 87 lbs worries me that maybe your suffering from an eating disorder. You should focus on toning and not so much losing or not losing much more since your already at a healthy weight.