Editing Help for locking a graphic to a certain point that moves

Hello everyone! I usually just edit videos together never really using graphics in the way I'm trying to use them on my latests project. I'm trying to have a line come out of a building and end up in another building across a river in a moving video. The problem is the line is locked to where it originally was created at the start of the video and the video moves so by the end the line has stayed at the exact spot but the building it has originated out of has moved. I know there is a way to make sure it stays on the original building, but I for the life of me cannot find a video that shows me how, and I'm sure it has to do with how I'm googling it. I've attached pictures of the problem.