Even though I try to part my bangs to the side, they keep falling back in the middle.
I keep trying to part my hair to the side, but it won't stay that way.
ーEven though I try to part my bangs to the side, they keep falling back in the middle.
「前髪を横に分けても、真ん中に戻ってきちゃう」
to part my bangs to the side で「前髪を横に分ける・流す」と言えます。
to keep falling back で「落ちてくる」この場合は「戻ってくる」と言えます。
ーI keep trying to part my hair to the side, but it won't stay that way.
「髪を横に分けようとするんだけど、戻ってくる」
to keep trying で「〜しようとし続ける」
it won't stay で「とどまらない・そのままでいない・持ちこたえない」=「とどまらないで戻ってくる」と言えます。
ご参考まで!