Hi,
When you are in VS or 5VS (Hybrid) mode, then you can use the modulation matrix to set Pressure to control Oscilator pitches.
Unfortunately there is no modulation matrix availble when in 5 mode.
Please consult your manual about the Matrix. Also learn about the routing in VS and 5VS mode, that's located in the Effect section.
Prophet V is one of the older Arturia applications. It could need a rebuild to make some things better and easier.