You should be able to find V4 theme by going Options/Preferences/Themes
If, for some reason, it's not there, I've uploaded it to GoogleDrive here:
reaper theme ? Google Drive
Download it, then pop the zipfile into Reaper/Install Data/ColorThemes
In V6, to change the monitoring default, go:
Preferences>Project>Track/send defaults
and click on 'record config'