When I try to drag a video clip next to another video clip, it doesn't let me, and a dashed blue horizontal line appears. I can't even put my timeline cursor there. Please help?
Could you show a screenshot?
It's a snapping indicator line. It's probably dashed because something's not quite quantized, but in practice is. It shouldn't stop you placing events wherever you want. Try zooming into the timeline more and/or temporarily turning "Enabling Snapping" off. A little discussion about snapping was here: https://www.vegascreativesoftware.info/us/forum/what-do-the-semi-transparent-lines-mean--99869/
So I think I see why. The two video files seem to be on an a and b transition.
So I was wondering how can I get them not to be on an a and b transition?
Try double-clicking the event boundary.
you are in the expanded track layer. Right click the Track header and uncheck "Expand Track layer"
Point 27. in https://www.vegascreativesoftware.info/us/forum/vegas-pro-faqs--104787/ helps you to know if you are in Expanded Edit Mode or have Expanded Track Layers.