You could edit the file /Setup/applications/mojoportal-core/FeatureDefinitions/10000_HtmlContentModule.config
to change the default value of those settings to true, then visit the /Setup/Default.aspx page to apply those changes.
After that any newly created instances of Html content feature will have the new default values. The only downside is you will have to edit that file again every time you upgrade mojoPortal.
The settings that would need changing in that file are:
<featureSetting
resourceFile="Resource"
grouNameKey="MainSettings"
resourceKey="ShowCreatedBy"
defaultValue="false"
controlType="CheckBox"
controlSrc=""
sortOrder="310"
regexValidationExpression=""
/>
<featureSetting
resourceFile="Resource"
grouNameKey="MainSettings"
resourceKey="ShowCreatedDate"
defaultValue="false"
controlType="CheckBox"
controlSrc=""
sortOrder="320"
regexValidationExpression=""
/>
<featureSetting
resourceFile="Resource"
grouNameKey="MainSettings"
resourceKey="ShowModifiedBy"
defaultValue="false"
controlType="CheckBox"
controlSrc=""
sortOrder="330"
regexValidationExpression=""
/>
<featureSetting
resourceFile="Resource"
grouNameKey="MainSettings"
resourceKey="ShowModifiedDate"
defaultValue="false"
controlType="CheckBox"
controlSrc=""
sortOrder="340"
regexValidationExpression=""
/>
change false to true
Hope that helps,
Joe