Column Widths in sheets?

What determines the width of each column in a sheet? I experimented a little by putting in 15 or 20 columns. I expanded some by clicking in the header and moving the arrow and that allowed me to scroll back and forth to view all of them. I closed the sheet, reopened it and the columns had returned to their original size. Would I have to somehow save it to preserve the sizes?

DT Pro automatically adapts the width to the contents after opening a sheet (except too wide columns which are limited to a certain width).

For example, import your addresses via File > Import > Addressbook… and select the resulting sheet. Most columns should be large enough to display all contents.

Thanks. I discovered that after I posted. It is still nice to have confirmation.