A few things to be aware of in Logic's score editor:
The parameters above only affect how notes are shown. Interpretation mode will try to show your notes you want to see them, but not necessarily in accurate way. No Overlap means that Logic will suppress the display of overlapping notes, but the overlaps will still be there. The same goes for Max. Dots. So if you want to see an as accurate version of your notes in the score editor as possible, you should turn off all these, including Quantize (which will quantise what is being displayed only, and not your actual MIDI notes). All this can be confusing at first, but IMO all these options are very useful.
Also – to see a more accurate display of your note lengths, you could enable the duration bars (you can also
edit the note lengths using these bars: they add a degree of piano roll functionality to the score editor).
Your score can look quite messy without using the 'make up' functions above, especially if it is recored in real time and not by using step input. Personally, I prefer to turn the duration bars of/off as needed (I have assigned them to D on the keyboard) and to have most of the parameters in the picture above on, and then switch between the piano roll and the score editor (using the keys P for piano roll and N for notation, no need to create screen sets actually) when needed.
But understanding how these parameters behave, and experimenting with having them on and off, removes some of the confusion re. what is actually being edited in the actual MIDI note vs. what is being changed only in terms how how things that is being
displayed in the score editor.
The green beam in the picture below is the so called 'duration bar'. Very useful.
You can also use these commands to change note lengths:
Nudge Region/Event Length Right by Nudge Value
Nudge Region/Event Length Left by Nudge Value
Nudge Region/Event Length Right by Tick
Nudge Region/Event Length Left by Tick
Nudge Region/Event Length Right by Division
Nudge Region/Event Length Left by Division
Nudge Region/Event Length Right by Beat
Nudge Region/Event Length Left by Beat
Nudge Region/Event Length Right by Bar
Nudge Region/Event Length Left by Bar
Nudge Region/Event Length Right by SMPTE Frame
Nudge Region/Event Length Left by SMPTE Frame
Nudge Region/Event Length Right by SMPTE Bit
Nudge Region/Event Length Left by SMPTE Bit
Nudge Region/Event Length Right by 1/2 SMPTE Frame
Nudge Region/Event Length Left by 1/2 SMPTE Frame
Nudge Region/Event Length Right by 5 SMPTE Frames
Nudge Region/Event Length Left by 5 SMPTE Frames
Nudge Region/Event Length Right by Sample
Nudge Region/Event Length Left by Sample
Nudge Region/Event Length Right by 1 ms
Nudge Region/Event Length Left by 1 ms
Nudge Region/Event Length Right by 10 ms
Nudge Region/Event Length Left by 10 ms
And (a favourite of mine), Sustain inserted notes:
This allows you, among other things, to change your note lengths when you enter them in step input mode from a keyboard, even before you lift your finger to trigger a note off message (!). This means that if you are going to enter ideas without a lot of triplets and not many notes that are shorter than a 1/16 note, you could enter notes really fast by setting the default input value to 1/16-notes, here...
...and then just extend them with Sustain Inserted Notes when needed, which in this case means that they'll become 1/16 note longer each time you use that command.
This way, your note will first change from being a 1/16 note become (sustained by it's original length, which is 1/16 note), an 1/8 note, then a dotted 1/8 note, then a 1/4 note and so on. It's easier than it sounds like.
AFAIK this is the fastest step input method available among all DAWs, at least on this planet, mainly because it allows length editing on-the-fly.