change date only if cell is changed

I have data in right column sorted as date and fields below... (attachment)...

If some of cell in E column is changed (selected from drop down list in cell) I need date to change into today. If not leave last date...

First time it look at E4 where is start date entered.
A Report that you start to write.

After that it look as it explained: if changed today() if not last date entered.

If someone change start date it shouldn't affect dates below (Start date shouldn't be changed but you never know

Every date should look only cells below it up to next date.