Yes as ur thyroid levels are well with in normal limits no need to change the dose u need to continue same dose. For cholesterol first treatment is always diet and exercise. U need to start exercise regularly and follow diet, reduce weight if overweight. Inspite of all this if still high then can start on treatment depending on ur age and other comorbidities.

U have to continue same dose if TSH is normal. For cholesterol the treatment needs to be prescribed by a doctor based on values