Quoting the online Finale manual:

• Tie Conversion: PostScript • Screen • Ask When Converting. These options are used when converting files previous to Finale 97 for determining how to handle ties. In versions before Finale 97 ties were represented differently on the screen than when they were printed on a PostScript printer. Because Finale 97 and later versions no longer have this difference, older files can be converted either using the screen representation of ties, or using PostScript settings of ties. You can also have Finale ask about converting ties during the conversion process by selecting the Ask When Converting check box.