Open PROMs → PROMs Settings to configure which PROMs are sent in the PROMs Schedule Matrix.
Each row is a procedure and each column is a timepoint. In each cell, tick the PROM instruments to collect for that procedure at that timepoint; leave a cell empty (No PROM) for none. Save the schedule.
When you add a new procedure, come back here and assign its PROMs — otherwise none will be collected for it.