gui design – Best practice for meaning of “return” in UI flow

For context in this question, I am recalling a programmable thermostat interface with four large buttons, two each on the left and right side of an LCD display. The display showed labels for the buttons, which changed depending on the mode. At a particular place in the “programming” sequence, the center of the screen had a flashing “Monday / Leave / 19C ” with “10:30” not flashing and the labels next to each button were: “Return” (upper left), “Save” (upper right), “-” (lower left) and “+” (lower right).

Does that upper left label mean “return” as in the common sense of “go back to where you were before / the previous step?” Or does it carry the programming sense of the word, “take this value back and continue to the next step?” On many keyboards, it seems the “return” key (also sometimes called Enter) is closer to the latter meaning. In this particular context, it could also mean “Instead of programming the ‘leave’ temperature, switch to programming what the temperature when the occupant returns/comes back into the space, when the temperature setting should return to what is desired for when the space is occupied.”

From this interface, it seems that pushing the + and – buttons would adjust the time set temperature but it’s not clear exactly what the meaning of “return” should be in UIs. In the particular instance motivating the question, the user had a very young child who had pressed some of the buttons on a thermostat the user did not have permission to program. The user wished to cancel out all recent changes and return to the previous state, without having personal memory of what all that state was, and the interface did not appear at all clear about how to accomplish that, if it was even possible.

Are there any standards or best practices published on this?