dynamic on 3rd beat of a held note

Thank you for the information regarding putting a crescendo on a held note - using nodes. I found this was already set and still don't get the dynamic required. I did set as default a etc.
As well I need a sudden dynamic change at the end of the held note. Since I can't put a dynamic instruction on the end of the 3rd beat [end of cescendo] of the held note I am unable to put the sudden change on the fourth beat.