First off, you can only change the settings on an AOL screenname if you're logged in as a master account: If your parents or guardian have set up specific limitations on your account, you can't change it (which makes sense, right?). The steps I show here assume that you do have permission to fine-tune access for an AOL screen name.

To start, log in to your AOL account and choose Keyword --> Go To Keyword from the top menus. Then type in "parental controls":

This shortcut takes you directly to the Parental Controls area:

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Now just click on the Screen Name you want to alter, and you'll see the specific controls for that account:

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The specific setting you want is Edit Time Online, which you can see on the bottom right. Click on it and you'll see how the account is setup:

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As you can see, this particular account doesn't have any timer limitations, but if I did want to set them (or disable them), I'd click on the Change these Settings link by the "Allow Custom Daily Access" option, at which point I could fine-tune things to my heart's content:

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That's all there is to it if you want to change the allowable times during which you can access America Online (AOL) on a given day or on specific days of the week.

Hope that helps out!