Excel - Allow Editing of only selected cells

I need to lock the majority of cells in a sheet and allow inputs on specific cells.  I have followed the directions to: 1) select the cells to keep unlocked, right click, choose Format Cells/Protection and uncheck the Locked box 2) select the full sheet, repeat the Format options but select the lock box, 3) select Protect Sheet and Select Protect worksheet and contents of locked cells and Select unlocked cells.  This is partially successful and works for most of the workbook, but doesn't prevent editing of the text.

What should I do?