In introductory college physics courses, it is important that students have a thorough understanding of vectors since several topics depend on vectors. When the test of understanding of vectors (TUV) was administered to the students completing the algebra-based College Physics I course, it was found that students had considerable difficulties in certain vector concepts. To overcome these difficulties, the question-bank for personalized adaptive learning (PAL) was modified. These modifications were implemented in a later semester for the students of the same course. In the current work, we present students’ performance on 12 questions on TUV for two semesters with a focus on improvement in students’ performance on graphic representation and determination of direction and magnitude of a vector presented in unit vector notation, understanding of graphical methods for vector addition, subtraction and multiplication of a vector by a negative scalar. This study presents the development of questions in PAL assignments which may be beneficial for the teaching community.