How can I properly pass excel objects to functions?

I am accessing an excel sheet from MATLAB to read in some data, do some processing and edit the sheet. I had an original approach that did everything in a single script. Some of the individual operations were useful so I decided to break them out into functions. Now any changes I make to the file aren't saved?

% Check inputs
p = inputParser;
addRequired(p,'optIndexList', @(x) numel(x) == numel(flagList))
addRequired(p,'flagList', @(x) numel(x) == numel(optIndexList))
addRequired(p,'svnInfo')
parse(p,optIndexList,flagList,svnInfo)
 
% Open excel
e  = actxserver('excel.application');
eW = e.Workbooks;
eF = eW.Open(filePath);
eS = eF.Sheets.get('Item','optIndexes');
eS.Activate;
 
% Find columns of interest
endCol   = eS.Range('A1').End('xlToRight').Column;
colNames = eS.Range(['A1:' xlscol(endCol) '1']).Value;
[~,colPos] = ismember('svnVersion',colNames);
svnCol = xlscol(colPos);
[~,colPos] = ismember('optIndex',colNames);
indexCol = xlscol(colPos);
 
% Get optIndex column
allOptIndexes = getAllOptIndexes('indexCol',indexCol);
 
% Create svn string
svnVerString = ['URL: ' svnInfo.url ', rev: ' num2str(svnInfo.revision)];
 
nOpts = length(optIndexList);
for iOpt = 1:nOpts
    optIndex = optIndexList(iOpt);
    [~,rowPos] = ismember(optIndex,allOptIndexes);
    svnCellAddress = [svnCol num2str(1+rowPos)]; % svnCol for optIndex of interest we're going to edit
    switch flagList(iOpt)
        case 0
            % SVN verison was unchanged
            % Do nothing
            continue
        case -1
            % SVN version was changed but the code is not working
            % Colour red
            eS.Range(svnCellAddress).Interior.Color = RGB([255, 199, 206]);
            eS.Range(svnCellAddress).Font.Color = RGB([156, 0, 6]);
        case 1
            % SVN version was changed and the code is working
            % Colour red and overwire cell contents
            eS.Range(svnCellAddress).Interior.Color = RGB([198, 239, 206]);
            eS.Range(svnCellAddress).Font.Color = RGB([0, 97, 0]);
            eS.Range(svnCellAddress).Value = svnVerString;                        
    end
end
 
% Auto-fit column
eS.Range([svnCol '1']).EntireRow.AutoFit;
 
% Save and close the sheet
eF.Save;
eF.Close; % close the file
e.Quit; % close Excel entirely
 
end

Functions thats are called.

function allOptIndexes = getAllOptIndexes(varargin)
 
% Manage flexible inputs
p = inputParser;
addParameter(p,'colNames',nan)
addParameter(p,'indexCol',nan)
parse(p,varargin{:})
 
e  = actxserver('excel.application');
eW = e.Workbooks;
eF = eW.Open(filePath);
eS = eF.Sheets.get('Item','optIndexes');
eS.Activate;
 
if ismember('indexCol',p.UsingDefaults)
    if ismember('colNames',p.UsingDefaults)
        endCol   = eS.Range('A1').End('xlToRight').Column;
        colNames = eS.Range(['A1:' xlscol(endCol) '1']).Value;
    else
        colNames = p.Results.colNames;
    end
    [~,colPos] = ismember('optIndex',colNames);
    indexCol = xlscol(colPos);
else
    indexCol = p.Results.indexCol;
end
 
% Get optIndex column
endRow        = eS.Range([indexCol '2']).End('xlDown').Row;
allOptIndexes = cell2mat(eS.Range([indexCol '2:' indexCol num2str(endRow)]).Value);
 
% Close excel
eF.Close; % close the file
e.Quit;   % close Excel entirely

If I do lots of these operations, the result is quite slow as excel is always being opened and closed.

e  = actxserver('excel.application');
eW = e.Workbooks;
eF = eW.Open('O:\Engineering\Motor_Modelling\Optimisations\optIndexRegister.xlsb');
eS = eF.Sheets.get('Item','optIndexes');
eS.Activate;

I trield to pass eF/eS to the second function e.g.

getAllOptIndexes(eF)

However, if I do this the changes I make to the excel are no longer saved? It's as if there are two instances of the file open. Can anyone explain this? How can I get around the problem of opening and closing excel?

Many thanks,

Ryan