I sometimes have lost interest in the question or do not want to think through every Detail of an answer of somebody. Since I don't want to be rude I accept an answer so other People do not waste their time. Is there a better way to deal with those situations?
Accepting is not mandatory. If the answer isn't helpful because you don't understand, then I hope you don't accept it, but instead, comment asking for more clarification (as long as it's within the scope of the answer. If it starts to get tangential, then posting a follow-up question is the recommended way)
Accepting an answer is not mandatory; do not feel compelled to accept the first answer you receive. Wait until you receive an answer that answers your question well.
Accepting an answer is not meant to be a definitive and final statement indicating that the question has now been answered perfectly. It simply means that the author received an answer that worked for them personally.