Oncheck of checkbox functionality working everywhere on gridview

I have a js which onclick of checkbox will copy row value from one to another.

But my issue it is working anywhere when I click on gridview, but it should only when I check the checkbox.

Here is my code below:-

 function FunClickTest(record, rowIndex, cellIndex) {
            document.getElementById("Txtconfirm" + (record[0].Sr_No - 1).toString()).value = record[0].Default_Allot;
    }

Also see my gridview for the reference

<cc1:Grid ID="GrdConfirmation" EnableTypeValidation="true" runat="server" Width="100%"
        ShowFooter="false" AllowAddingRecords="true" AllowSorting="false" AutoGenerateColumns="false"
        Serialize="false" FolderStyle="Styles/Grid/style_12" CallbackMode="false">
        <ClientSideEvents OnClientSelect="FunClickTest" />
        <TemplateSettings NewRecord_TemplateId="ButtonsTemplate" MultiRecordSaveCancel_TemplateId="" />
        <Columns>
            <cc1:CheckBoxSelectColumn ShowHeaderCheckBox="true" ControlType="Standard" Width="5%">
            </cc1:CheckBoxSelectColumn>
            <cc1:Column ID="Column111" DataField="MKEY" HeaderText="Select" ReadOnly="true" Width="5%"
                runat="server" Visible="false">
                <TemplateSettings TemplateId="TemplateWithCheckbox" />
            </cc1:Column>
            <cc1:Column ID="Sr_No" DataField="Sr_No" HeaderText="Sr No" Visible="true" Width="5%">
                <TemplateSettings TemplateId="tplNumbering" />
            </cc1:Column>
            <cc1:Column ID="Line_Id" DataField="Line_Id" HeaderText="Line id" Visible="true"
                Align="center" Width="5%" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Item_Mkey" DataField="Item_Mkey" HeaderText="Item Mkey" Visible="true"
                Align="center" Width="5%" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Item_Code" DataField="Item_Code" HeaderText="Item Code" Visible="true"
                Align="center" Width="5%" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="ITEM_DESC" DataField="ITEM_DESC" HeaderText="Item Description" Visible="true"
                Align="center" Width="10%" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Lot_Batch_No" DataField="Lot_Batch_No" HeaderText="Lot / Batch No."
                Visible="true" Align="center" Width="5%" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Exp_Dt" DataField="Exp_Dt" HeaderText="Exp Date" Visible="true" Align="center"
                Width="5%" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="QTY1" DataField="Qty" HeaderText=" Quantity" Visible="true" Width="5%"
                Align="center" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Bx_Bg" DataField="Bx_Bg" HeaderText="Boxes/Bags" Visible="true" Width="5%"
                Align="center" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Net_Wgt" DataField="Net_Wgt" HeaderText="Net Weight" Visible="true"
                Width="5%" Align="center" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="NO_OF_PALLETS" DataField="NO_OF_PALLETS" HeaderText="No Of Pallets"
                Visible="true" Align="center" Width="5%" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Default_Allot" DataField="Default_Allot" HeaderText="Allocated Storage Bin No."
                Visible="true" Width="5%" Align="right" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="Confirmed_Allot" DataField="Confirmed_Allot" HeaderText="Confirmed Storage Bin No."
                Visible="true" Width="10%" Align="right" Wrap="true">
                <TemplateSettings TemplateId="TextBoxEditTemplate" />
            </cc1:Column>
            <cc1:Column ID="DAMAGED_QTY" DataField="DAMAGED_QTY" HeaderText="Damaged Qty in Units"
                Visible="true" Width="5%" Align="right" Wrap="true">
            </cc1:Column>
            <cc1:Column ID="SHORTFALL_QTY" DataField="SHORTFALL_QTY" HeaderText="Shortfall/ excess qty in units"
                Visible="true" Width="5%" Align="right" Wrap="true">
            </cc1:Column>
        </Columns>
        <AddEditDeleteSettings AddLinksPosition="Bottom" NewRecordPosition="Dynamic" />
        <Templates>
            <cc1:GridTemplate runat="server" ID="TextBoxEditTemplate">
                <Template>
                    <input type="text" name="TextBox1" id="Txtconfirm<%# (Container.RecordIndex) %>"
                        class="excel-textbox" value='<%# Container.Value %>' readonly="readonly" onfocus="GrdConfirmation.editWithTextBox(this)" />
                </Template>
            </cc1:GridTemplate>
            <cc1:GridTemplate runat="server" ID="tplNumbering">
                <Template>
                    <b>
                        <%# (Container.RecordIndex + 1) %></b>
                </Template>
            </cc1:GridTemplate>
            <cc1:GridTemplate ID="TemplateWithCheckbox">
                <Template>
                    <asp:CheckBox runat="server" ID="ChkID" ToolTip="<%# Container.Value %>" />
                </Template>
            </cc1:GridTemplate>
        </Templates>
    </cc1:Grid>