Select the Context Menu of any data block.

Select Choose columns.

On the resulting slide out panel, drag and drop a column to the data block on the right.

Repeat step three as many times as needed.

On a data block column, you can remove the column by clicking on the column itself, then click on the Remove icon. Removed columns return to the Data Block: choose columns list on the left.

Click Done.

There are pre-made data blocks that load upon opening a project in Plan's Quantity Tracking Module (in Data Block view). Each type of data block has its own unique default settings. Default settings include specific columns and total number of columns and panels.