When you've finished using it, make sure you always put it back where it was.
Every time you use it, please put it back where you took it from
Make sure you always put it back when you've finished using it.
「使ったらその都度、元の位置に戻してください」＝ When you've finished using it, make sure you always put it back where it was. / Every time you use it, please put it back where you took it from / Make sure you always put it back when you've finished using it.
「都度」は「each time」でも大丈夫ですが、「always」や「every time」という言い方も使えます。
ボキャブラリー
finished using ＝使い終わった（ら）
make sure ＝ 必ず～をする
put it back where(how) it was / put it back (where/how you found it) ＝ 元の場所・位置に戻す
イギリス 
