By default, sub-stats on artifacts are not checked (see notes section below regarding Unwanted Flat Stats). Selecting any of the stats will require those stats to be on the artifact; otherwise, it will be immediately sold.
Setting the mode selection to “Desired” will require at least one of the selected stats to appear as a sub-stat on the artifact; otherwise, it will be sold.
Setting the mode selection to “Required” will require that all selected stats appear as sub-stats on the artifact; otherwise, it will be sold.
If any Unwanted Flat Stats options are set, they will be checked even if no Required Main Stats are chosen.
When selecting stats in “Required” mode, you will be limited to the number of possible sub stats based on the lowest possible rarity artifact you will keep. If your lowest minimum rarity is Rare, you will only be able to select up to two sub-stats.