Huh, I guess I never noticed that the settings for Chord Quality / Major and Minor and “appearance of major seventh” aren’t the same. I would think the same options should be available in both locations. Anyway, there’s a pretty easy workaround provided you don’t actually need MA7 in your project and only want ma7.
Start by selecting the uppercase MA for the appearance of Major 7ths, even though that’s not what you want. In Engraving Options/Chord Symbols/Project Default Appearances hit Edit. Enter CMA7 and hit +. Click the MA in the CMA7 that appears on screen. You’ll notice the smaller MA will be selected underneath too. Click the Edit Component pencil which will now let you make a global change to the MA definition. In the Edit Chord Symbol Component window that just opened, delete the MA by hitting the trash can, go to the Text tab, select font.chordsymbols, enter “ma” then click Add Text. You’ve now redefined the MA symbol to be ma globally in your file. Hit OK, then Apply and you’re done.
(Bonus points for anyone that recognizes what tune the above progression is from. They are all maj7(#11) chords in the original.)