于是 vs 所以

所以 draws the logical conclusion (很冷，所以我不想出去); 于是 narrates the next move — "thereupon" (于是出现了一个问题).

于是於是

yúshì ㄩˊ ㄕˋ

thereupon; as a result; consequently; thus; hence

于是出现了一个问题，哪里能找我们需要的机器。

Then arose the question of where we were to get the necessary machinery.

所以

suǒyǐ ㄙㄨㄛˇ ㄧˇ

therefore; as a result; so

外面很冷，所以我不想出去。

It's cold outside, so I don't want to go out.

In LinZi, pulling up a comparison is one tap inside a review, no context switch, no lost queue position.