PCs change models so quickly that you have to constantly relearn them.
"PCはすぐモデルチェンジするのでまた覚える必要がある"
- PCs change models so quickly that you have to constantly relearn them.
- PCs change operating systems constantly so you have to constantly keep learning about them.
- You have to constantly familiarize yourself with new models (or operating software) because PCs change so quickly.
Laptops change models so quickly that it's necessary to relearn them.
ご質問ありがとうございます。
この場合「PCは[すぐ](https://eikaiwa.dmm.com/uknow/questions/33807/)モデルチェンジするのでまた覚える必要がある」と言いたいなら、英語で「Laptops change models so quickly that it's necessary to relearn them.」と言えます。
ご参考になれば幸いです。
アメリカ合衆国 
