Does changing Voice Memo audio quality affect previous recordings, or only new ones?

This is a question about the consequences of changing Voice Memo audio quality settings

my devices -- iPhone 13, iOS 17.6.1 // iMac 24, Sonoma 14.6.1

I use Voice Memos a lot for recording musical ideas / guitar / singing / demos. I have over 3000 voice memos. (they are synced to iCloud, and I regularly back them up on a hard drive)

As of now, the audio quality setting is on "Compressed", which is the default setting.

My question -- if I were to change the audio quality setting to "Lossless", would that convert the audio quality of all prior recordings, or just the ones I make after switching to Lossless?

I know Lossless takes up significantly more space, so with 3000+ memos I'm concerned about a huge increase in storage being used up.

One more question -- say I open Voice Memos on my iMac and change the audio quality setting there -- would that change apply to the memos on my iPhone as well? Since the recordings are stored in iCloud, I would assume that whether I open the app on my phone or my computer, the recordings are "playing from" iCloud, either way, if that makes sense... in which case I would assume that changing the audio quality on one device would mean that the quality is changed across all devices.

Grateful for any help on either of these questions! I bet there are some musicians out there wondering the same thing. Thanks!

Ian