Answer
Follow these steps to change the font type for new annotation text or existing annotation text in a PDF with Foxit PDF Editor or Foxit PDF Reader：
To change the font type for new annotation text:
1: Select the one of annotation tool under the "Comment" tab ,such as typewriter,textbox. Single-click on a blank area in the PDF page where you wish to add new text. The cursor will start blinking, indicating that you can add new text here. Alternatively, if you want to add text to an existing annotation text, go to "Edit" tab> choose "Select">"Select Annotation" tool, double-click on the existing annotation text to enter into editing annotation mode,you will find that your cursor will start blinking on the location where you will add new annotation text.
2: On the right format panel, click on the font type triangle icon under the text style tab. This will bring up the fonts list in a drop-down menu. Select your desired font from the list.
3: Input new text at the location where your cursor is blinking.
4: If you want to set the currently selected font as default, go to "Comment" tab> choose "Select">"Select Annotation" tool,right-click on some annotation text that already uses the current font. In the context menu that appears, select "Set Current Properties as Default".
To change the font type for existing text:
1: Go to "Edit" tab> choose "Select">"Select Annotation" tool, double-click on the existing annotation text to enter into editing annotation mode,you will find that your cursor will start blinking.
2:Please Press Ctrl+A on your keyboard to select all of the annotation text in the existing annotation.
3:Look at the right format panel and click on the font type triangle icon under the text style tab. This will bring up the fonts list in a drop-down menu. Select your desired font from the list. The selected text in the existing annotation will change to the chosen font.
Note: If the Format tab does not open, click on the triangle at the extreme right of the page. You will find it somewhere in the middle of the page. This will open the Format tab.