By default, ExperimentName, Subject, and Session appear as the first three variable columns. The remaining variables are organized alphabetically within hierarchical log levels. That is, session level variables occur in alphabetical order after the first three columns, then the variables for the next log level (e.g., Block) are organized in alphabetical order, then the variables for the next log level (e.g., Trial) are organized in alphabetical order, etc. The default column order is used every time a file is opened (i.e., any reordering of columns is not saved when a file is closed), or when the Restore Column Order or Restore Spreadsheet commands are used.
Refer to GENERAL: Saving/Loading Column Arrangement (.cd3)  for information pertaining to loading frequently used column definitions.