Is there a symbol that makes only 1 certain note sound soft or no?

Is there a symbol that makes only 1 certain note sound soft or no?

I use Sibelius so I don't have an assured answer, but have you tried "pp sub." on the the note then putting a "f sub." (or whatever the dynamic was previously) on the note after it?

Is there a symbol that makes only 1 certain note sound soft or no?

If you are using Finale, create an expression. Click the "mf" (Expression Tool) and create an expression with the Key Velocity that you want. (If you don't know how to do this, let me know.)