You can change the width and height of the row or column in your sheet that everyone sees in the Design Mode. Firstly, click on the "Change Design" button on the upper-right hand corner to enter the design mode. Move your mouse cursor to the first row of your grid (the row that says A,B,C,...) and point at the right border of the cell you would like to adjust. Your cursor will display that the width of the column is adjustable. You can now Drag the cell border to change the width of the column, like the way you do it in other spreadsheet softwares like Excel.
Remember to save your form design after you're done. When the design changes are saved, the changes will be applied to everyone's view on this sheet.
You can also change the width and height without entering the design mode while looking at a form by dragging the locations where the row and column definition borders would be in the design mode, but these changes will not be preserved next time you see this sheet.