I am a new user of PE12. I am coming from using PPro 2. Whenever I alter earlier in the timeline the program moves all clips on all tracks forward the same number of frames. For example, if I want to insert a clip in slow motion, once it throws everything off. Since there is no way to lock the tracks, this pretty much forces you to edit in a linear manner which kind of defeats the purpose of having a NLE program. Is there a way to stop that from happening?
What computer operating system is your Premiere Elements 12 running on? Have you gone from the 12 to 12.1 Update of the program via its Help Menu/Update? If not, please do so. Just background for now.
To the arrangement of clips on the Timeline matter....
As you hold down the Alt key of the computer main keyboard, you add/drag media to an existing Timeline to avoid disturbing the existing Timeline content.
When applicable, you can select a group of clips all at one time, right click any where in the selection, and apply the Group command from the pop up menu to group the clips. Then the clips will move as a group.
There is a free video tutorial on this type of matter. The principles in it should be interesting for you and applicable for different versions of the program. I post the link to it for informational and not promotional purposes.
If you want to select clips more than one at a time, lots of ways, but try, with the mouse cursor, drawing a rectangle around the clips that you want selected all at one time.
Please review and consider.
We will be watching for your results. Any questions or need clarification, please do not hesitate to ask.