It's really up to you on which battery settings fits your needs. I would suggest reading Dell Power Manager User's Guide thoroughly before making such decision.  Dell Power Manager User's Guide | Dell US Also, if you haven't done so yet, update latest Dell Power Manager app onto the computer. You could do this by clicking on your Dell model number in the link below. After, you should be able to see latest Dell Power Manager for your computer in your Dell Product Support page. Drivers & Downloads | Dell US 
I bought Dell Inspiron 3501 Core i5-1135G7 one week ago, I have 2 questions, 1) If I use my laptop while it's plugged in ,will it decrease the life span of the battery? 2) Which one is better between these two-
Using my Laptop keeping it plugged in