Here's a little "general-purpose tip" for Pico users. I've got a 4423 scope, & while it's really nice to have 4 channels when needed, most often I'm using 2 (typically Volts & Amps on whatever I'm testing). More often than I care to admit, I grab my scope, hang it up (I made a protective sleeve with hook), hook up my leads, & stare at flat lines on my laptop screen. I recheck my connections- still no change.

After cursing & grumbling awhile I LOOK at my leads- hard, then curse some more, slap myself on the head (Gibbs-style ) & move my leads from jacks D - C (CH4 & 3) to jacks A - B where I get now get a pattern

. I tried putting a BIG letter A on the scope sleeve by that jack, added bright orange paint there as well. No good.
I can't tell if I just "can't help myself" or if I'm "beyond all help"

.
I did come up with a solution that works. I took a piece of soft/clear PCV hose (about 3/8" ID-thinwall) & cut it to 1/2" long. I then drilled two small holes 180* apart about 1/8" from one end to fit over the lugs on a BNC jack. Put a little dielectric grease on the inside of the hose & I can "pop" the hose over the jack for CH4 to remind me where NOT to hook up. It easily comes off if I do need CH4.