When you open the Universalis application on Android, you will see a page of text with three controls at the top.

Near the top left you will see the date you are viewing. If you tap on it then a calendar will appear which lets you go to any date you want. Instructions are here.

Towards the right you will see the name of the page you are viewing. If you tap on it then you will see a list of all the available pages, including all the Hours, the readings at Mass, and so on.

At the far top right you will see three dots. If you tap on them, a menu will open, with three options in it:

If you don't see the three dots, you must be using a device with a physical menu button: in which case, press that button.

Options in the text

Here and there in some of the pages, you will see a pale blue arrow on the right-hand side. These arrows let you choose among various options within the page.

Universalis tries to be intelligent in remembering your choice. For instance, if you chose to have the Invitatory Psalm at Morning Prayer today, it will show it to you at Morning Prayer again tomorrow. Of course, if it has guessed wrong, you can use the blue arrow to correct it.