Hello Marcello11756,
Here's my answer. Yes it is possible to edit only one column in a grid, but in order to achieve this, you have to make other columns Read only. On screen designer, click on edit grid and go to step 2 of 9: Grid Columns. On each column, click on Advanced and select Make Read Only option(except the column you want to edit). Then, go to step 5 of 9:Allow Edit? and click Editing takes palce directly in the grid, Finish it and save it. This should help in editing on the grid.
Hope this helps!
-Inder