Don't know if this helps you but did you already try changing Disk IO Type to Simple pread/pwrite (in advanced settings)? It was meant to address some issues with disk read/write + RAM usage. Not something that affected me all that much but could be worth a look.
Was mentioned in the 5.0.1 release notes and in the github pages
https://www.qbittorrent.org/news
https://github.com/qbittorrent/qBittorrent/pull/21300
Beyond that I'd echo the other comment, try to just change settings you actually need to change. Oftentimes people make a whole ton of settings changes in their torrent client and then can't figure out how to get it back to normal.