Makes sense. Most of ours do not either.
From there, like you said, go to company config; then right-click on the GL Code for AR Account, and open the Entry app. (Someone here 10 years ago decided “Default” would be a great name for everything. 
)
Then you want the “Receivables” row of Account Context (because “Receivables” is what is in bold in the guide here)
For us it’s this account.
