Hi, I’m a beginner of glyphs app, I saw some tutorials on youtube and noticed that every metrics lines would show up on the background. However, when I draw lowercase letters, the cap height lines are not appearing in my background. What settings do I need to change?
I love this. This has been a recurring discussion with everybody complaining that not all metrics are shown in all glyphs (cap height not shown in lowercase, etc) ever since some update where they started to be hidden (why? No idea). In the latest update, all metrics are shown again (but without alignment zones). Again, why? No idea.
The end result, after enough complaints, will probably be the return of all metrics and alignment zones at all times 
You can find numerous threads here on the forum discussing this.
I did find a method suggested by others and it seems to work for me now. But I don’t know if there will be a problem with the font after exporting?
That’s right, I really don’t understand why, it’s obviously a good auxiliary tool, why cancel it? why? 
Hopefully a future update will bring them all back. Thanks for your reply!
That workaround is technically possible, yes, but I would recommend against it if you are not 100% sure of what you are doing. This can mess up your exports.
Make sure to use vertical metrics (hhea and typo) and set these in each master, otherwise, Glyphs will be unable to accurately set them on export and your font will be positioned oddly in text setting applications.
See here: Vertical Metrics | Glyphs
You can also use the script Vertical Metrics Manager (Install the mekkablue scripts from Window > Plugin Manager > Scripts > mekkablue)
Update to the latest version (3.1) and the standard metrics are shown in all glyphs. Do not delete the standard metrics as that causes issues on export (unless your font is only using a script where metrics such as x-height do not apply, then it is save to remove the unneeded metrics).
