Library vs Explore
Library holds your current program, programs, Saved Workouts and exercises. Explore is the catalog.
A program is a multi-week plan. It sets which days you lift, which exercises run on each day, and how the weights move from week to week. 5/3/1 Strength and Push Pull Legs are programs, and so is anything you build or import yourself.
Grain Gym keeps track of your week and day. The cursor moves forward when you finish a workout, and the targets for the next one come from the program's rule. Your programs live in Library, under Programs.
A workout is a single session. When you start a program day, Grain Gym builds that day's workout from the plan, with its exercises, sets and targets. When you finish, the workout goes into your history.
A Saved Workout is a session you want to run again without a program around it. It isn't tied to a week or a day, so you can start it whenever you like.
Make one in Library under Saved Workouts, import it from JSON, or save a finished workout with Save as Saved Workout in its menu, or Save as workout on the summary screen.
Use a program when you want a plan to run for weeks. Use a Saved Workout for the session you repeat, such as a travel day or a garage finisher. Library vs Explore shows where each one lives.
Library holds your current program, programs, Saved Workouts and exercises. Explore is the catalog.
Replace an exercise from its menu, then choose whether the swap lasts one workout, one day or the whole program.
Open a session from History, choose Edit Workout, fix the sets, and save. Your PRs and training max update to match.