Ancient Hebrew is a very descriptive language but the problem is translating it to English, sometimes our words cross meanings with it and we have one word for two meanings. An example is our word Lord; Hebrew has two completely different words for what we call Lord – Adonai and Yahweh. The NIV translation will use the word Lord but with two different cases to represent the two Hebrew words – LORD and Lord. The preface in the NIV Bible has a great explanation of why the translators did this.
From the Zondervan NIV Exhaustive Concordance we get the meaning of Adonai as the one true God who has majesty and authority and Yahweh as the one true God that makes personnel and covenant relationships, the name also gives the picture of a God who exists or causes existence. Psalms 68:17-20 uses both of the words so replace the word Lord with a form of its meaning and see how it changes the idea of the passage.
The James Moffatt Translation uses the word Eternal instead of Yahweh (Lord) and I always felt that it was very powerful in the way it changes the passage. So try replacing the word Eternal when you see the word Lord especially if you read the NIV translation.
(see The Lord my/your God)