User settings are stored in ~/.config/pcmanfm-qt/lxqt/
Custom actions can be created in ~/.local/share/file-manager/actions/
More details in Wiki manjaro. Some custom actions are available here.
For all details see PcManFm-qt Wiki
PavuControl-qt
User settings are stored in ~/.config/pavucontrol-qt/
LXimage-qt
User settings are stored in ~/.config/lximage-qt/