This paper focuses on Partial and Synchronized Caption (PSC) as a tool to train L2 listening and introduces new features to facilitate speech-related difficulties. PSC is an intelligent caption that extensively processes the audio and transcript to detect and present difficult words or phrases for L2 learners. With the new features, learners can benefit from repetition and slowdowns of particular audio segments that are automatically labeled difficult. When encountering high speech rates, the system slows down the audio to the standard rate of speech. For disfluencies in speech (e.g. breached boundaries), the system generates the caption and repeats that video segment. In our experiments, intermediate L2 learners of English watched videos with different captions and functionalities, provided feedback on new PSC features, and took a series of tests. Smart repetition and slowdown components received positive learner feedback and led to significant improvement in L2 listening recognition. [For the complete volume, "CALL and Professionalisation: Short Papers from EUROCALL 2021 (29th, Online, August 26-27, 2021)," see ED616972.]