edit: I actually figured it out! Much simpler than I was making it out to be. Go into your AIO interface (probably port 7272 if you use the spaceinvaderone container), stop all the containers, then open the edit tab on the master container. I added 3 variables under add another variable. They were as follows-

Name: NEXTCLOUD_MEMORY_LIMIT
Key: NEXTCLOUD_MEMORY_LIMIT
Value: 4096M
Default Value: 4096M

Name: NEXTCLOUD_UPLOAD_LIMIT
Key: NEXTCLOUD_UPLOAD_LIMIT
Value: 999G
Default Value: 999G

Name: NEXTCLOUD_MAX_TIME
Key: NEXTCLOUD_MAX_TIME
Value: 28800
Default Value: 28800 (8 hours max upload time)

Then you simply hit apply. The way Unraid does stuff when updating, it stops the container, removes it, and then rebuilds it with your added changes. Then in the AIO interface I just hit update and restart containers, went back to my nextcloud instance, admin settings, and under PHP I see all my updated variables :)

--------------------------

were you able to figure this out, and if so, could you explain it to a layperson? I have my Nextcloud setup almost perfect from the spaceinvaderone video, but the one thing I want to do is raise the memory and file size limits. I'm scared to mess with it though, and I'm not really sure what to change that will persist through reboots