The default columns that you see when you create an account are "Date", "Status", "Owner", "Full Name", "Phone" & "Email". Although these are the most common lead details you might want to change their position or add / remove the columns.
To do so first click on the "Wrench" Icon on the top right corner of the leads table, then choose "Edit Table" from the drop down menu.
In the "Edit Table" popup, you can drag & drop columns from the "Inactive" section to the "Active", the top column in the "Active" section is the most left column in your leads table. You can also drag & drop columns in the "Active" section to change current column positions.
Dragging a column from the "Active" to the "Inactive" section will remove the column from the leads table.
You can easily rename a column by double clicking on it, after typing a new label just click anywhere on the screen and the change will apply.