Hello dear,
It is so simple to increase or decrease the size of your text with out going to the menu.
Just select the text and Press "Ctrl + ]" Keys and increase the size of the font in the same way if you want to decrease the font size just Press "Ctrl + [" Keys to decrease the size of font.
There is another way to increase or decrease the size of text.
Select the text you want to increase just Press "Ctrl + Shift + >" and increase the size that you want. In the same way Press "Ctrl + Shift + <" to decrease the font size.