First, stop dragging and nudging!
Next, locate the Align button. It is in several locations: Home tab, Drawing group, Arrange button and on the Format and Picture tools contextual tabs in the Arrange group. Select objects and choose the alignment style you prefer. If you want objects to begin at the same vertical location on the slide, select Align Top.
If you need objects evenly distributed horizontally, place the first and last ones at the left and right. Select them all and choose Distribute Horizontally.