The difference between flat and threaded......
flat means that each topic is listed ....threaded means each topic is broken down.....you can click on each and see the difference yourself. Some people prefer to skim each post to see a topic of interest ....others read each one. It is a personal preference.
Expanded means that each post is spread out for you to skim through.....collapsed means that it looks neater and you can go through and read which post you want to read.
Myself, I have the board collapsed and the threads in flat mode but you can change it to whatever you want. Try clicking on each and seeing which one you prefer. You can always go back into your profile and changing it back if you don't like it that way.
This stuff is fun to learn and we are never too old for that

Heather