I took time to fully explore my B3n
with the book, and discovered several things i didn't really used until today. One of them is the master level.

And here is my question: i already have raised levels of my different patches with effect volumes and patch levels.
And now i realize that the master level is around 32 / 100 ..
In your opinion; would it be better to raise the master level 90 to 100 and adapt my patches level after ? Or let it as it is: master level at 32, and my patches around 100 ? What would be the difference ?
What do you do with yours ?
Thanks !
The reason I use the following method is to make sure that, if an emergency happens where I need to physically bypass the B3n (take it out of the signal chain), there isn't a crazy fluctuation in level that needs to be adjusted. Also, if using the pedal with a traditional bass amp, it helps the bass amp's input "see" a similar output level as it otherwise would if plugging directly from the bass alone. Adding too much gain from a pedal, even if the tones are all very clean within the pedal, can seriously overdrive the input of a preamp unless it has sufficient input padding (not always the case).
Here's what I do:
1) determine the output of my bass going directly (no effects or anything else in line) into the input of the speaker system you use (I prefer a full range speaker system based on PA cabinets). (A simple way to get in the ballpark is to set up a mic aimed at the speaker system and plugged into a DAW, and then see where the levels register at the input of the DAW.)
2) plug the bass into the B3n, and put it in tuner BYPASS mode, so that only the dry signal is passing through the pedal. Then try your best to match the output level of the tuner-bypass signal with that of the direct bass (in part #1 above).
3) when creating patches, for every effect, amp, cab, processor you add to the virtual signal chain in the B3n, compare the output level of each effect with that of the tuner-bypass level. When using amps and drives, it is very easy to tend to add level. If you are setting an amp/cab model in the B3n for "nominal" (typical) output level, then the amp/cab sims should be set as to NOT boost the overall output much, if at all. If you do want a boost to the signal, use the amp model' BOOST switch setting for this purpose, or otherwise put a drive stomp/boost effect in the chain that has the specific purpose of BOOSTing the level.
Otherwise, with an amp/cab sim and other standard effects engaged, there shouldn't be huge fluctuations in overall output level, again, unless a boost from an effect is specifically desired. This can also be a little tricky since not all effects have a dedicated Level parameter.
When using amp/cab modeling, it is a general rule of thumb to make it a workflow habit of ALWAYS checking each effect and combination of effects (and amp/cab sims, etc.) in relation to dry bypass through the unit. This holds whether you're using an inexpensive Zoom pedal, or something that costs $2000.