Changing font style, size, color and alignment requires a highlighting of the text you need to change fonts to.
To change font size - see attached screens - select the text and choose a size from the list of sizes.
Or, select the text and manually enter font size - click on top on the white border - image attached.
A double click on a word inside the text box will highlight it automatically.
Check the box to
Use Paragraph icons to align text in your box.
See images attached. They open in new tabs.