I set the margins of my document in Word at 2 cm but in part of the document the text passes over the right border

Despite that the page margins for a document in Word were set to 2 cm for top, bottom, left and right, part of the text passas over the right margin, even outside the paper width.

I do not know how to set the little triangle which elsewhere appears in the ruler at the right margin, as that thing is absent over there.

Can anybody give me a suggestion how to clear this problem.