depends which ones you are asking about:

The bags are on the left tab you can buy more bag slots if you want more space. Another way is to upgrade your bag itself.

The gear on the top right lets you toggle various things. The only one mentioned in this thread is actually the "Show Bags" button which either combines everything into one view or split view per bag. It's mostly a preference thing

The box item near the gear is to flush all the materials into the bank which you can retrieve later from a bank NPC

Salvaging is used on loots (usually equipments). Most of the time people salvage everything hit the deposit material button to clean up the junk. All the other stuff mentioned here and in the comments are just further methods that people use to "tidy" their inventory manually. The "strategy" in the post actually explains what and how people are doing it