Anyone? Help, please?

Followup: the problem is getting back to "construction mode" after building on the initial vacant lots.

Once you have built a building, how do you get back to construction mode?

Many thanks in advance for any constructive assistance.

The game does not give me the option to upgrade buildings--which has the effect of making it unplayable. I have started it several times--I get the option to upgrade a single building, but after that the button disappears.

Suggestions?

Thanks . . .

Kevin