You should be able to select what you do and do not want to use in the Smart Trim feature after AutoAnalzyer analysis of the sample followed by the appearance of the selected areas and right click of each to make a selection of Trim, Keep, Select All, .....
There is a YouTube video tutorial on Smart Trim by Chad Perkins (uses version 11 but should be comparable to version 13)
That is a strange looking link hope it works.
If the link does not work, I found it in Firefox in the following Google Search for Using Smart Trim Premiere Elements 13.
I will try the link after I post this reply.
Thanks, ATR. The video was very helpful. Better than the one I found on YouTube.