调整 (tiáozhěng) is the most common, general verb for 'to adjust, to modify' — used for schedules, plans, attitudes, etc. It is broader than 调 (tiáo), which typically means to tune a device or reconcile a relationship, and 调节 (tiáojié), which focuses on regulating a system or process (e.g., temperature, emotions). 调剂 (tiáojì) specifically means to balance or improve a state (e.g., mood, pace).