In the Develop Module go to the first photo and remove the crop using the Crop Tool (Keyboard shortcut - R).
Next, be sure that the first photo is still selected. Click on it in the film strip and confirm that the border is white.
Next, hold the shift key and click on the last photo in the film strip which will cause all of the photos to have a white border which is darker than the first photo which is the "most selected" photo.
Now the "Sync Settings" button will turn white and you can click it. In the Sync dialog click the Check None button.
Next place check marks in the Crop and Process Version boxes
Finally click Synchronize.
I suggest that you read Martin Evening's and/or Scott Kelby's book(s) on Lightroom 4.
