1. The temperature and type of yeast used will yield the results. But you have to remember few things.
2. The dough has to be slightly sticky, elastic and soft. Knead it well but don not overdo.
3. Let the dough rise till it doubles. It might take more of less time depending on where you live and which yeast you use.
5. Once you cut the donuts, cover and let it rise till it doubles again.
6. Deep fry on medium heat. When you add donuts, the oil must be slightly bubbling. Fry for a minute or two on each side. This ensures that the donuts are cooked on the inside without changing the color fast and without becoming soggy.
You can also cut them into circles without holes in center. The disks without holes makes it perfect for filling. The cream filled donuts in the pics are the donuts without hole in center.
You can also let the dough rise in the refrigerator anywhere from 6-15 hours. Then roll and shape. Cover it loosely and let it rise till the donut doubles in size, about 2-3 hours.
Pastry cream can be stored in the refrigerator for 2-3 days.
Homemade donuts taste better the same day. It can get soggy as it sets. Managing steady temperature(350 Degrees F) and frying on each side for 1-2 minutes is key to avoid soggy donuts.