How to create a circuit that has a long lifetime but has a variable? Answered

Hi, I am looking at a parallel circuit that includes a power supply by 3 AA batteries and powers 30 LEDs (Being sold like so).

I want to convert the same supplies to series circuit powered by  the same 3 AA batteries however the amount of LEDs could vary from 1 to 30. Would this still be functional and not burn out the LEDs?

The overall project is designing a series circuit that can have different amounts of LEDs in it. I would like to know if I need to change the power supply for each situation (and how to do that easily) or if it would work fine.

Thanks!