Check your course module outline, or ask your tutor how they would like your assignments formatted. If you can't find this information, then the below guidelines have been taken from the Publication manual of the American Psychological Association: The official guide to APA style (7th ed.) (the Manual).
All papers should have a title page (you may have been provided a template in your module outline). All pages should be numbered (top right corner) and often you are expected to include your student ID number on each page too. If you are handing in a paper copy, you may need to ensure you only print on one side of the page (check your tutor's preferences).
All margins (top, bottom, left, and right) should be 2.54 cm (this is the default 'normal' setting on Word). However, some tutors might like your left margin to be much bigger (e.g. 4 cm) to allow for marking. Also, if you are intending to get your assignment bound, you need to allow space on the left-hand margin to allow for this.
The entire paper should be double spaced, except:
Postgraduate students and those of you publishing your work, refer to the Manual for specific information.
APA style allows for a range of accessible fonts to be used, but be consistent and use the same font throughout your paper. However, it would be advisable to stick to 11-point Calibri or 11-point Arial throughout your assignments.
Text should be aligned left, so that your right margin has an uneven "ragged" look. Don't use full justification, otherwise your words will be unevenly spaced across the page.
Indent the first line of every paragraph by using the tab key.
See the Manual for further information.
Appendices contain material that supplements your paper, but would be distracting or inappropriate to include within the body of your text. For example, if you interview someone for your research, you might want to include the transcript of the interview in an appendix.
Appendices go at the very end of your assignment after references, footnotes, tables, and figures. Begin each appendix on a new page and provide a label and title for each. If you just have one, label it Appendix. If you have more than one, label each with a capital letter e.g. "Appendix A", "Appendix B", in the order mentioned in the text (note, each appendix needs to be mentioned at least once within the text by it's label, e.g. "see Appendix A"). Labels should be bold and centred. The appendix title should describe its contents and also be bold and centred, but on a separate line from the label. Use title case for both the label and title.
According to the Manual, your word count should include the entire document from the title page to the appendices. However, for the purposes of an assignment, we would only expect your word count to include the text (and in text citations) of the body of your work, not the title page, contents page, reference list nor appendices. As always, double check with your tutor to find out their preference.