Here's a rewritten version of the provided text in an easier-to-understand format:

If you're experiencing issues with your Mac getting stuck at the loading bar, try following these steps to resolve the problem.

1. Allow your computer time to fully boot into its operating system.

2. Once it has loaded completely:

- Ensure that you are on the correct hard drive by selecting 'Macintosh HD' from the available options and pressing 'Return.'

3. When you see the Startup Manager, use either of these methods depending on your situation:

a) If only one startup disk is showing up:

i) Use the left or right arrow keys to cycle through any other hard drive options until Macintosh HD appears.

ii) Press Enter (or Return).

b) If multiple startup disks are visible:

- Ensure that you're booting from the correct Startup Disk by clicking on 'Apple Menu' > System Preferences > `Startup` > `Restart`.

c) Hold down Command + Option/Alt keys while turning on your MacBook until the Apple logo appears. Release these keys once you hear the startup chime for a second time.

4. If none of the above steps resolve the issue, try resetting NVRAM (non-volatile random access memory):

- Turn off your Mac completely.

- Immediately press and hold down Command + Option/Alt + P + R while powering it back on.

- Keep holding these keys for about 15 seconds until you hear a second startup chime or see the Apple logo appear again with an outline around the clock icon.

Mac stuck at loading bar