If you follow a threading video and do it along with the video, starting and stopping and repeating as needed, over and over again for one sit-down session of it, you will learn to thread (and change thread colors) your serger easily.
On Youtube, type in your Brother Model name and threading.
I have taught thousands of people how to do it this way.
This enables you to use your serger without anxiety about threading.
How I thread my Brother 1034d Serger by Candice Ayala
How to Thread the Brother 1034d Serger (Sewing Report)
Threading Brother 924d/1034d Serger
Lower Looper Brother M343D and1034DX
Info.pdf (updated 01-02-2018)
Additional Thread Info
Cleaning Thread Tension Channels