There is brief summary of Japanese translation in written form.
You should try not to use”～ない” when you can use affirmative sentence.

Usually negative sentences will have a certain effect when it used in warning sentences, when under the instructing or urging others to do things it should be try to use affirmative sentence, to ensure a proper expression.
e.g. 掃除する時に、使わない箱などは残らないでください。

This sentence is very cumbersome, the correct version should be:
掃除する時に、使わない箱は捨ててください。

Please not to use double negative as possible as you can.

e.g. 画面が切り替わらない時は、操作の順序を間違えたと考えられなくもない。

We all know that double negative means sure, but use too much negative parts in sentences, you can not make it clear to everyone. So you should use affirmative expression in sentences as possible as you can.

Read Also: The Foreign Language in Japanese

And the correct expression of the sentence should be:

画面が切り替わらない時は、操作の順序を間違えた可能性がある。

The similarities and differences between “場合”and”時”.

e.g. インターネットで注文するとき、2週間以内に配達を希望する場合は…
When there is only one precondition, it should use”時”more often, if there are more than two preconditions, the first condition should use ”場合” , and the others use “時”.

So the correct expression of the sentence should be:
インターネットで注文する場合、1週間以内に配達を希望するときは…

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