How can my ldl be high but my triglycerides be low?

Cholesterol: Depending on the levels you can do diet and exercise if they are not very high or medications if these are high

Different fats: Triglycerides & cholesterol are different types of fats in the blood. Some people have both high LDL “bad cholesterol” & high triglycerides, but many people have high LDL with normal triglycerides. Diet changes can help lower LDL but you may also need medication (statin drugs are 1st choice). Genetics play a role in elevated cholesterol & triglycerides in many cases, & that cannot be changed