For example, how testosterone makes your larynx grow to change your voice and makes you store fat in a masculine distribution among other things, but how exactly does it “tell” the body to do those things? And same with the effects of estrogen.
Each cell in your body has the same DNA
However each type of cell has a different set of molecules that activate genes called transcription factors.
Sex hormones, or any hormone, bind to these transcription factors. Since these factors are different in each cell, they each activate a different gene. This way one hormone released throughout the body can have specific effects in each cell.
Hormones cause changes in target cells by binding to specific hormone receptors in the cells. Some cells will only have certain receptors and the quantity of receptors can change as well (like a key and lock). Some hormones can enter the cell and bind to DNA to regulate gene transcription. They basically change the way the cell reads its instructions to make the cells do different things. Some hormones bind to receptors on the outside and trigger signaling pathways that change the production of various cell products that affect the cell in the short-term.