Increasing icon size in panel launcher / taskbar

[Roderick Johnstone]

Hi

This morning's surprise after having to restart my system because 
nouveau had locked up under my locked plasma 5 session (F22) with 
gazillions of messages like:


kernel: nouveau E[   PFIFO][0000:01:00.0] PBDMA0: ACQUIRE
kernel: nouveau E[   PFIFO][0000:01:00.0] PBDMA0: ch 2 [Xorg[978]] subc 
0 mthd 0x001c data 0x00001004

(the nouveau lockups are no longer a surprise, unfortunately)

is that the icons of the launchers in my panel and task bar entries for 
running programs have become very small.

I've been though many of the obvious menus in system settings changing 
plausible setting, applying and logging out and in again but the icons 
don't change size!

Can anyone advise how to increase the size of these icons please.

Thanks

Roderick