Keyboard shortcuts in an app make it easy to use. Many apps work perfectly without them, but they are welcome wherever they are available. If an app developer does so that users can customize the shortcut and put it to what they want, it's even better. That said, for more complex applications such as Photoshop or the Office Productivity package, custom shortcuts are not possible. More importantly, it is not easy to teach them everything. Button Shortcuts is a free menu bar app that can display all keyboard shortcuts for an app. All you have to do is press the Command key twice.
Show the shortcut keys for an app
Download the hot keys from the Mac App Store. It will run in the menu bar and at first boot, the app will guide you through the features.
Once you have gone through the guide, switch to which app you want to use. When you need to use a hot key but don't remember what it is, press the Command key twice. Button shortcuts open a small menu where you can browse all available keyboard shortcuts for an app. You use keyboard shortcuts in a particular app more and more, you will eventually begin to remember them. When this happens, it may be counterproductive to have the special hotkey in the list, and therefore you can send it to the bottom of the list. To do so, click on the green mark next to the list.
If there is a particular shortcut you always have trouble remembering, you can favor it. If you do, you will tap it at the top of the list in the menu, making it much easier to find. There is also a useful search box in the app's window that you can use to search for a hot key.
If you later begin to forget a shortcut, you can click the green badge next to it and it will be added back to list. Likewise, once you have learned a shortcut you favored, you can click on the green mark below it and have it sent to the bottom
Every time you have a new, functional app that you have to wait for, this app comes to to be useful. It has no settings for you to manage given it's a pretty straightforward app.
If you learn a new app, you may learn their hot keys faster if they are visualized on-screen every time you use them.