#include<array.au3>
$sIniFile = @ScriptDir & '\test.ini'
$sSearchText = 'Значение4'
$sReplaceText = 'Значение5'
$aSection = IniReadSectionNames($sIniFile)
For $i = 1 To $aSection[0]
$aReadSection = IniReadSection($sIniFile, $aSection[$i])
$aIndex = _ArrayFindAll($aReadSection, $sSearchText, 1, Default, Default, Default, 1)
If Not @error Then
For $j = 0 To UBound($aIndex) - 1
IniWrite($sIniFile, $aSection[$i], $aReadSection[$aIndex[$j]][0], $sReplaceText)
Next
EndIf
Next