Click the bullet area of the slide canvas to select the bulleted text block, and then click again within one of the words in the text block to place the insertion point in the text.
Choose Edit > Select All to select all of the text in the text block
Click the Fonts button to activate the Font panel if it not already visible.
In the Family list, click the font Arial Narrow, and in the Typeface list, click Regular.
Drag the Size slider downward in the Font panel until all of the words fit in the text block. A point size of 30 or 31 should work.