Changing Watermark opacity in Gimp 2.10

[TuxfordC]

Having successfully used Gimp to recover a couple of thousand elderly pages for
archiving - and my thanks to Ofnuts for his help on this project - I now need to
watermark them before the archive goes on line.

Have read several tutorials about watermarks using Gimp, and  made progress
towards a batch operation - except for adjusting the watermark opacity. There was
a tool for changing opacity in earlier versions of Gimp - where is it in 2.10 please,
or has the procedure changed?


Thanks,
Tuxford.