Ask Questions and Find Answers

I think, you can find the checkboxes here:
Control Panel -> Configuration -> System Settings (Content and Data) -> Dynamic Data Mapping
Control Panel -> Configuration -> System Settings (Content and Data) -> Web Content -> Administration
Uncheck the autogenerate structure/template key checkboxes.

Thank you Christoph, that's correct!
As additional info, I've exported configuration files and put them inside osgi/configs directory of my application server:

• com.liferay.dynamic.data.mapping.web.configuration.DDMWebConfiguration.config
  

  autogenerateStructureKey="false"
  autogenerateTemplateKey="false"
  changeableDefaultLanguage="false"

• com.liferay.journal.web.configuration.JournalWebConfiguration.config
  

  autogenerateDDMStructureKey="false"
  autogenerateDDMTemplateKey="false"
  changeableDefaultLanguage="false"
  defaultDisplayView="descriptive"
  displayViews=[ \
    "icon", \
    "descriptive", \
    "list", \
    ]
  journalArticleForceAutogenerateId="true"
  journalArticlesSearchWithIndex="true"
  journalBrowseByStructuresSortedByName="true"
  journalDDMTemplateLanguageTypes=[ \
    "ftl", \
    ]
  journalFeedForceAutogenerateId="true"
  maxAddMenuItems="7"
  showAncestorScopesByDefault="false"
  showFeeds="false

I've just realized that the above configuration works only for Widget Templates...for Web Content Structures and Templates does not work and keys continue to be autogenerated. Any suggestions? Thank you

I've found that the configuration is correct, but probably Liferay has a bug.
In the images attached, you can see inside red rectangles what appears in the interface with the above configuration: a not resolved language key for structures and only a label for templates: in both cases no input text fields at all to set a custom key.
I've found a workaround with a groovy script, updating the structure/template key after their creation:

def structureName = "EXISTENT-STRUCTURE";
def newStructureKey = "NEW-KEY"; def query = "UPDATE DDMStructure SET structureKey='"+newStructureKey+"' WHERE name like '%"+structureName+"%';";
def result = com.liferay.portal.kernel.dao.db.DBManagerUtil.getDB().runSQL(query); 

and

def templateName = "EXISTENT-TEMPLATE";
def newTemplateKey = "NEW-KEY"; def query = "UPDATE DDMTemplate SET templateKey='"+newTemplateKey+"' WHERE name like '%"+templateName+"%';";
def result = com.liferay.portal.kernel.dao.db.DBManagerUtil.getDB().runSQL(query);

---
EDIT: I've opened a related bug to this.