You'll never forget the day you went out and bought that set of fluffy, soft towels that was just perfect for your bathroom. It probably never gave out a musty odor or felt scratchy against your skin. All of these are symptoms of using too much soap or fabric softener.
Powders lose their efficacy when exposed to moisture in the air, rendering them less useful. The problem could be solved by transferring the detergent from its cardboard box into an airtight container and only opening the container when adding detergent to the washing machine. If you notice any clumps, rub some of it between your palms to test if it will generate heat, and if not, throw it away.
In the case of liquid soap, compare the total ounces to the number of loads advertised. Depending on the type of soap, this converts to about 1.4–1.8 ounces. About 8 ounces is all you need of liquid fabric softener. Only use one pod each load unless it is exceedingly dirty or you have a huge load of clothes. Dryer sheets should not be used in conjunction with liquid softener.
Follow these instructions to get your towels back into fluffy and soft condition.