"Peak hold" is a function that can be selected on some LED VU meters. The highest bar remains lit for a time while the rest of the meter functions normally. You have to make sure the feature is present and enabled.

I'd scour the manual to see whether there is a way to increase the output of those low-level patches. And regardless, I'd put a compressor-limiter in the chain. It would tame those 'peaky' patches while helping raise the output of those with lower volume.

HTH,

R.