Firstly, I need to know which report viewer you use. Based on the description I suspect that it's the WPF viewer. If you want to change the position of the parameters, I suggest to modify the XAML theme (Telerik.ReportViewer.Wpf.xaml file). Then you need to refer it locally.
For further information, visit Setting a Theme (Using Implicit Styles) article.
If you use another viewer, I will need more details about the desired outcome.
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