Locking List Columns
Lists can contain many columns. You might find that you want to scroll horizontally across a list to view additional columns without losing focus of the first few columns in the list. In this scenario, you can lock the first few columns. Columns that are locked have a lock icon in the column header to indicate that the column is locked.
To lock list columns
Navigate to the list where you want to lock columns.
Click the header of the column that you want to lock.
Click Lock.
A lock appears in the selected column and in all columns preceding the selected column (if there are any). You can scroll across the remaining columns without loosing focus of the locked columns.
To unlock list columns, click the header of the last locked column (which is beside the first unlocked column), and then click Unlock.
The lock disappears from the selected column and in all columns preceding the selected column.