DIP switch 10 switches between ID022 and ID023, which are different communication protocols. Different IGT games call for one protocol or the other.
On the technical side of how the protocols communicate with the machine, the signal sent for $1 bill acceptance between ID022 and ID023 is nearly identical, and is close enough that you can generally cheat a $1 bill through with the wrong protocol selected. As such, if the symptom is that a $1 bill is accepted, but all other bills that the DBV is capable of accepting are held for a second or two then rejected, it often is the case that the wrong protocol is selected (and is fixed by switching the position of DIP switch 10 on the DBV). There could be other issues, such as a credit limit setting on the machine, but DBV DIP switch 10 is a good first suspect.