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Invensys thermostats were made by Robertshaw - Attached is a programming & user manual for the 9700 series. You should be able to bypass the programming schedule by putting the thermostat in temperature hold. Instructions for setting the current day and time vary depending on the model. With a model number or sometimes even a picture of the thermostat we might be able to find the manuals for your specific thermostat.
The Invensys Day and Night was a mechanical clock style thermostat - not a digital programmable model - The face of the thermostat looks like a clock face. If this is what you have I'll have to do some research to find the literature. Day and Night might also refer to a brand of equipment made by Payne for a number of years and then later made by United Technologies - The term Day and Night on the equipment (indoor or outdoor) is a marketing brand and doesn't really indicate any special features of the unit.
Isolating the bedrooms from the living area would depend on the unit design and duct system - sometimes the systems are installed with dampers which would allow airflow to be controlled independently to each ducted zone but they are typically used in larger homes and not found in smaller systems (like apartments). It might be beneficial to have a local service contractor or even the apartment maintenance tech schedule a visit to evaluate the system, see exactly what you have, and explain what options you have for better comfort control.