Here are the errors in the sentences:

2. "make" should be "to make."
The corrected sentence: "No one had any idea about how **to make** a craft with only a few bamboo canes."

3. "into" should be "for."
The corrected sentence: "Their daughter said that she doesn’t want to take exams **for** economics universities."

4. "confused" should be "confusing."
The corrected sentence: "I don’t know what to do as these instructions are extremely **confusing.**"

Feel free to ask if you need further clarification!