Refractometer feature

Hello friends,
Having just completed my first BeerSmith brew, I'm trying to understand the refractometer tool feature. I selected "fermenting wort" and entered my original gravity of 1.066 and received an corrected gravity of 1.023. Please excuse my naivete as to what's going on here. Is BeerSmith automatically calculating the time since the beer was brewed(7 days)? Will it continue to do so? What should I do now? Obviously, I'll check the fermenting wort to see if it's 1.023. I used only the SG, not Brix. How about this feature in general? Should I rely on it, or go back to the hydrometer? I'm brewing half batches, so I don't want to waste. Thanks! Cheers!

The fermenting wort option tells you, given your original gravity, the final gravity of your beer. It is adjusted for the fact that refractometers do not accurately measure the brix with alcohol present. You must use the fermenting wort option if reading with the refractometer if the sample is fully or partially fermented. If you go back to the hydrometer, it reads well regardless of alcohol presence.

You are giving it your sample's gravity (measured in brix scale) along with the OG which you obtained earlier when you pitched (in specific gravity scale). Recall that when pitching you used the unfermented wort gravity option, giving it the sampled brix and obtaining OG in specific gravity scale. (Or perhaps used your hydrometer to get the OG, either way).