Who is meant by 'you' in the poem "Still I Rise" by Maya Angelou is American society in general and the thoughts held by some in this society. She addresses, for example, those who record history, whether its academic historians with prejudices against black people; newspapers and magazines with the same intent, or anyone or any group that records in a malevolent way stories about black people and their particular organizations.
You may write me down in history
With your bitter, twisted lies,
It is obvious in these lines that she is taking historians and others to task for their prejudicial writings and oral storytelling. These are those who report inaccurately and sometimes totally wrong the history and contemporary stories about black people and their life experiences.
She challenges these people, asking them (this subset of society) if her being sassy upsets them. She talks with confidence and lets these people (who subscribe to putting blacks down) know that she will not be defeated by them, that she will counter them confidently and win.
Maya Angelou also writes:
You may cut me with your eyes,
You may kill me with your hatefulness,
This refers to peoples detestable looks full of animosity towards blacks as they may pass a black person in the street, in a mall, or wherever. This also refers to the deaths that have occurred against the black race in the form of lynching parties and other heinous acts.
We can tell that Maya Angelou is addressing society in general in this poem, in that she does not single out any one individual or group particularly. The 'you' of the poem is a general, all-encompassing term meant for this specific prejudicial group in society.
Nonetheless, someone of this ilk who may read this poem, may take this 'you' personally. Therefore, as an alternative, the 'you' can in some cases be addressed to a specific reader. It depends on who the reader of the poem is, as others who read this poem may not feel it is addressed to them at all.
Hence, this is why overall, the poem is addressed to that entire segment of American society that has untoward feelings, thoughts and actions towards blacks and to their culture, and sometimes act wrongly towards black people because of these proclivities.