Some time ago Gmail used to open with each main label 'closed', i.e. with nested labels indicated only by a horizontally-facing triangle. Now, though, Gmail opens with everything open to the max – and since I have a great many nested labels, it is a mess. I have to page down the labels column for maybe a meter before getting to something that starts with e.g. N. This is time-consuming and frustrating. Is there any way to make Gmail open with sub-labels closed by default?
Gmail – Collapse nested labels by default
gmailgmail-labels
Related Solutions
If you are using filters to apply the labels, then it should be possible is to create another filter to apply a second label to all the messages. You can then use this second label in your search criteria.
better use HTML basic or try reverting to the older look you can do so by using the settings {gear icon} dropdown just above your inbox on the right hand side 
or in new Gmail look go to the settings in settings dropdown menu then to labels tab and in labels click on show against each label you want to have on Gmail home screen
for old look {if it isn't available in the settings menu}you could just go to settings menu and select compact to have a similar look though you can make it more akin by using an appropriate theme
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Best Answer
You mention:
The now default behaviour is to have the main labels at the state (extended/collapsed) as were left by the user.
This means that if the last time you visited gmail the main labels you (the user) left open will still remain open until manually closed (by clicking the little triangle) by you (the user).