--- a/src/ai/ai_core.cpp
+++ b/src/ai/ai_core.cpp
@@ -47,6 +47,7 @@
 		/* Load default data and store the name in the settings */
 		config->Change(info->GetName(), -1, false, true);
 	}
+	config->AnchorUnchangeableSettings();
 
 	Backup<CompanyByte> cur_company(_current_company, company, FILE_LINE);
 	Company *c = Company::Get(company);

--- a/src/game/game_core.cpp
+++ b/src/game/game_core.cpp
@@ -71,6 +71,8 @@
 	GameInfo *info = config->GetInfo();
 	if (info == NULL) return;
 
+	config->AnchorUnchangeableSettings();
+
 	Backup<CompanyByte> cur_company(_current_company, FILE_LINE);
 	cur_company.Change(OWNER_DEITY);
 

--- a/src/script/script_config.cpp
+++ b/src/script/script_config.cpp
@@ -84,6 +84,15 @@
 	this->settings.clear();
 }
 
+void ScriptConfig::AnchorUnchangeableSettings()
+{
+	for (ScriptConfigItemList::const_iterator it = this->GetConfigList()->begin(); it != this->GetConfigList()->end(); it++) {
+		if (((*it).flags & SCRIPTCONFIG_INGAME) == 0) {
+			this->SetSetting((*it).name, this->GetSetting((*it).name));
+		}
+	}
+}
+
 int ScriptConfig::GetSetting(const char *name) const
 {
 	SettingValueList::const_iterator it = this->settings.find(name);

--- a/src/script/script_config.hpp
+++ b/src/script/script_config.hpp
@@ -108,6 +108,16 @@
 	};
 
 	/**
+	 * As long as the default of a setting has not been changed, the value of
+	 * the setting is not stored. This to allow changing the difficulty setting
+	 * without having to reset the script's config. However, when a setting may
+	 * not be changed in game, we must "anchor" this value to what the setting
+	 * would be at the time of starting. Otherwise changing the difficulty
+	 * setting would change the setting's value (which isn't allowed).
+	 */
+	void AnchorUnchangeableSettings();
+
+	/**
 	 * Get the value of a setting for this config. It might fallback to his
 	 *  'info' to find the default value (if not set or if not-custom difficulty
 	 *  level).