Hallo @inthefields und herzlichen Willkommen.
For your fretless, with the active preamp if it's a 3 bands model, choose the bridge pickup, put the mids almost to the max, add a bit of bass (just after the center click) and remove a bit more of highs thanyou did with the bass. You'll start to have that mwah growling, slightly adjust to your taste all 3 bands.
If you can choose between full humbucker or single coil, opt for single coil.
If your preamp is a 2 bands, slightly boost the bass and roll back the highs.
That said a mid control is almost mandatory on a fretless as it's the mwah control.
Roundwounds also sound à la Jaco, when flatwounds have a great tendency to kill that mwah.
Other tricks next time. 😉
By the way, I'll turn 56 this year, so you're not old.