You cannot change sensor readings taken in Graphical Analysis or Spectral Analysis apps, but you can edit manual-entry data or columns of data typed in Events Based/Selected Events mode. Sometimes it is tricky to edit those entries, especially to change the left-side of the entry. Here are some notes to help with this:
On Mac and Windows and Chromebook: Go to the Table view and double-click the cell. If you want to modify a part of the entry other than the end, use the left arrow key on your keyboard to move the cursor.
On iOS: Go to the Table view and double-click the cell. The on-screen keyboard should appear. If you want to modify a part of the entry other than the end, press and hold down on the space bar part of the keyboard display as you slide your finger left. This is a standard iOS user interface, introduced in the Fall of 2018.
On Android, double tap on the table entry. The on-screen keyboard should appear. The on-screen keyboard has arrow keys that look like ‘<‘ and ‘>’ at the lower right. Move the cursor with those arrow keys.