When you use Surfer's Map Tools | Layer Tools | Track Cursor command to click on points on a post map and highlight the nearest point in the worksheet document, the X and Y columns must be assigned correctly in the worksheet.
Go to the worksheet window and click Data | Data | Assign XYZ Columns. Make sure the X and Y columns are assigned to the same columns used to create the post map, and click OK.
Now go to the plot window, click Map Tools | Layer Tools | Track Cursor (if it isn't already enabled) and click on a location on the post map. The nearest point to the location you clicked will now be highlighted in the worksheet. You may wish to use the View | Windows | Tile Vertical command to see the plot and worksheet windows side-by-side.
Updated October 26, 2017