Should you mention the undergraduate degree you dropped out from when?
A2A Transcripts are necessary to verify degrees. If you went to several universities as an undergraduate, your transcript with your Bachelor's degree shows the courses an grades. As for graduate work, you would include all transcripts without giving any explanation. You do not write a Personal Statement for Graduate School, you write an SOP supported by LORs that documents your accomplishments and what you hope to accomplish if admitted. Degrees are accomplishment especial if you have done a thesis: coursework alone are not. Your transcripts documents coursework accomplishment in a cumulative and major GPAs. You also have standardized test that help rank applicants relative to one another. Of the three, your SOP is the most important and it will make or break you when compared to the other applicants. For a general discussion see, How to improve my chances to admitted into a top University that everyone under the sun wants in. by J. Lee Anthony on How to get into the University of your choice.