Why is the name “the LORD” substituted for Yaweh?
The Jews came to view the name of God YHWH to be too holy to be spoken in common language. For this reason, in Hebrew versions of the Old Testament they substituted the Hebrew word for The LORD for YHWH. This tendency goes all the way back to biblical times. Even today, if you read the writings of many Jews, they will write G_d rather than God as a way of showing reverence for the name of God. We might view this as silly and unnecessary, but probably we would do better to respect the Jewish tendency to honor God in this way, even if we do not imitate the specific way they honor God.