Parent problems

I recently moved back in with my parents due to the fact that school just got out. My parents always told me that ever since I graduated high school that I’d have more freedom but that hasn’t been the case. I told them multiple times that I’d be going to help a friend out with his house and that I planned on staying over night for a few a days because it’s an hour drive. I went over to my friends house and my parents kept calling and texting actin like I never mentioned it to them (they told me that I didn’t have to ask for permission to go anywhere but had to let them know who I was with and where I was going). They told me stay the night with him and then said I had to leave the next day and that they would talk to me when I got home. Now this friend of mine has health problems and didn’t have anyone else to help him. I’m 18 btw and I get that I have to follow their rules while I’m staying with them but I was told multiple times that I didn’t have to ask for permission and let them know where I was and who I was with. They always do this to me and ask me a million questions even if I’m just going around to corner to the grocery store but my brother who is 16 is allowed to go wherever with whoever and they don’t treat him the same way they do me. I don’t even know what to say to them in order to get my point across any advice or ideas?