There are lots of things that can get in the way of a character's goals in a story. If the impediment is another human being it probably stems from one of two things. Arguments can arise over trivial things and this can lead to reaching of a goal from an indirect method, but those are just side issues and not the true source of the conflict.

Scarce Resources

There is only so much of anything to go around and if two characters both want it then we have a conflict. This isn't something that will happen all the time but stories aren't about anytime, they are about those moments of conflict. If characters that are in conflict with each other, there is a good chance it's over things they want to get that only one can have.

If you want to use the car and so does your sister, that's a conflict. No matter if you try to argue with her over the tone of voice she's using or how it's too hot in the room, ultimately you do so in an attempt to get to use the car. These are tactics of creating other lesser conflicts with the hope of wearing down the other character so they will let you get what you want. Or you may take this time to work out a mutually beneficial plan and she starts to insult your manner of dress or your dirty finger nails. She doesn't really care about that stuff. That's not what the conflict is really about. Those are tactics to achieve the overall objective: get to use the car.

Incompatible Goals

In life we can't always do things on our own. Not only does it take two to tango, it's take two to carry heavy things. A character may find him or herself in a position where they need to get another character to do something for them that this other character is unwilling to do. You want this person to help you, so you take all sorts of measures to get them on your side. You will bring up past things done for them, bad things this character does that the other character has thus far ignored, or maybe even threaten them.

You need your brother to take you to the repair shop so he can take you home while the car is worked on but he refuses. You will do all manner of things to try to get your way. You can promise to not help him the next time he asks for help or you can tell him you will embarrass him at the earliest chance you get. You can break something of his and indicate you will break more stuff if you don't get your way. When you want someone to do something you can't just keep asking please and pretty please. You need to put them in a situation where they see that not helping you is worse than helping.

When characters are chatting there are often conflicts they are working out. Underlying them are scarce resources or incompatible goals. A character wants to get something or make another do something. It's easy to get mixed up in all the banter and never resolve what the character is really after and this can leave your story with a false feeling. As long as you keep in mind the real thing your characters in the story are after you'll be able to lead conversations and actions back to where they ought to be, just like we do in life.