Your AO2 bands are about how you use evidence in relation to your argument. These are just a few tips about how you can improve.
AO2 - 7-10 marks "Evidence of detailed research involving the selection and evaluation of a wide range of relevant resources. Critical analysis and application of the resources with clear links made to appropriate theories and concepts."
"Detailed research" - use quotes with lots of specific detail. This might be an interesting or complicated stat/number/piece of data. It could also be the use of a particular word, such as "destructive" or "rebellious", which adds more detail and explanation to the point that the author is trying to make. Please note that this 'detail' should be relevant to the argument you are making in some way, and not just randomly selected.
"selection and evaluation of a wide range of relevant resources" - This section of the mark scheme is talking about two things. The fact that you should have a "wide range" or "relevant sources", and the fact that you should select them carefully and evaluate them. A "wide range" of sources could be interpreted as many things. It could be different types of sources (videos, books, websites, online lectures, pictures etc). It could also refer to using sources from many time periods (from primary sources at the time, to secondary sources from many different time periods). It could also refer to using a variety of authors, cartoonists and artists who fundamentally believe in different things (different approaches to history, different political views). However, make sure that these sources are "relevant" at all times and contribute to the body of your text. The "selection" and "evaluation" of your evidence is about how you use the evidence and your personal take on the sources.
" Critical analysis" - Analyse the source. What is good about it? What are some of its drawbacks? Do you agree or disagree, and why? Do you think the author/artist goes far enough with this argument? What are the effects of this source being a picture/cartoon/table of data? When was it produced, and why does it matter? Who was the author/artist, and why does that matter?
"application of the resources" - This is about using the evidence and making it work for you. If you have a quote from a book that is relevant to the point you are making, use the quote. Also explain why you have used it and how the criticism of the quote could be relevant to your point. For example, if the quote was written by a communist, the information in the quote may be useful to making your point, but the tone of the quote might imply a different perspective to your argument. Try to use one source you disagree with (and prove why your opinion is better), one source you really agree with (and your evaluation of the source can help strengthen your argument), and one source you do not completely agree/disagree with (you might feel it does not go far enough in making its point etc).
"clear links made to appropriate theories and concepts" - Be explicit about themes, motifs, ideologies that the sources make reference to. Explain the link between the quote and the theory/concept, and how that fits into your argument. The criticism of your source could be vital in the link between the source and the theory/concept. Demonstrate your knowledge between linking various events/evidences/points of view.
I hope this has helped. Once I know more about the specifics of your "History EPQ", I can see if I help even more.