The DEC VT220 terminal does not support more than 132 columns; therefore, VersaTerm does not allow you to display more than 132 columns.
The Text Emulation Option in Extras (Settings menu) should be set to VT220/8-bit mode when on a DEC host (VAX, VMS). Otherwise, host applications that drive the terminal using cursor addressing will display strange characters.
A DEC VT220 terminal is not a color terminal. VersaTerm assigns colors to particular styles (Bold, Italics, etc.). These settings are controlled in the Text Attributes dialog (Emulation menu).
The difference between a VT220 and VT240 terminal is support for Regis graphics (a DEC proprietary low resolution graphics format). If you try to use VersaTerm with a program on a host that uses Regis graphics, it will not work. If you can set the terminal type on the host so that Tektronix graphics is used instead of Regis, VersaTerm should work fine.
Protocol converters - many need you to be set to 7 data bits and Even parity in order to function properly.