Hey Jarena,
You cannot really modify the EAs “by hand”, but what you can do is to optimize the EAs.
You can do it in MetaTrader or in EA Studio:
Go to EA Studio – Help – Strategy – Optimizer.
There is a video and there is a detailed explanation on how to do it.
Now, be careful, not over-optimizing your strategy (making it too perfect).
Yes, when you use TP you are limiting the potential of the trade but at the same time, you are securing some profits. Both have PROs and CONs.
Regards,