how to make with apache + autoindex for *.txt files are downloaded and not opened

in the htaccess for that directory
/foo/.htaccess:
RemoveType .txt

no, this not work
after have added this in .htaccess is same. and same if I add this in httpd.conf.

same this not work.
this is my mine part in my conf apache 2.4.3 :

<IfModule mime_module>
    TypesConfig conf/mime.types
    AddType application/x-compress .Z
    AddType application/x-gzip .gz .tgz
    AddType application/x-httpd-php .php .php3 .html .htm
    AddType text/html .gx .pube
    AddEncoding x-gzip .gz
    AddType application/x-javascript .js
    AddType text/css .css
    AddType text/xml .xml
    #AddHandler cgi-script .cgi
    #AddHandler type-map var
    #AddType text/html .shtml
    #AddOutputFilter INCLUDES .shtml
    AddType audio/mpeg     .mp3 .MP3
    AddType audio/playlist .m3u .M3U
    AddType audio/x-scpls  .pls .PLS
    AddType audio/ogg .oga .ogg .spx .OGA .OGG .SPX
    AddType video/ogg .ogv .OGV
    AddType application/ogg .ogx .OGX
    AddType audio/flac .flac .FLAC
    AddType audio/annodex .axa .AXA
    AddType video/annodex .axv .AXV
    AddType application/annodex .anx .ANX
    Addtype application/xspf+xml .xspf .XSPF
    AddType texte/x-composant .htc .HTC
    AddType application/download-me .txt
    <files *.js.gz>
      AddType "text/javascript" .gz
      AddEncoding gzip .gz
    </files>

    <files *.css.gz>
      AddType "text/css" .gz
      AddEncoding gzip .gz
    </files>

    <files *.xml.gz>
      AddType "text/xml" .gz
      AddEncoding gzip .gz
    </files>
</IfModule>

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can you please check what contentype header is send to your browser (use a FF add-on like firebug, LiveHTTPheader, etc.)

with firefox file txt is downloaded but not with IE, Chrome, Opera.

http://*********/too.txt

GET /too.txt HTTP/1.1
Host: ************
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20100101 Firefox/13.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: fr,fr-fr;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://********/
Cookie: __utma=259398038.5993309.1306913933.1317908675.1326825895.27

HTTP/1.1 200 OK
Date: Mon, 28 Jan 2013 10:00:34 GMT
Server: Apache
Last-Modified: Sat, 26 Jan 2013 01:47:44 GMT
Etag: "c-4d4273aee0b89"
Accept-Ranges: bytes
Content-Length: 12
Keep-Alive: timeout=15, max=40
Connection: Keep-Alive
Content-Type: application/download-me
----------------------------------------------------------

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http://*********/too.txt

GET /too.txt HTTP/1.1
Host: ************
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20100101 Firefox/13.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: fr,fr-fr;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://********/
Cookie: __utma=259398038.5993309.1306913933.1317908675.1326825895.27

HTTP/1.1 200 OK
Date: Mon, 28 Jan 2013 10:00:34 GMT
Server: Apache
Last-Modified: Sat, 26 Jan 2013 01:47:44 GMT
Etag: "c-4d4273aee0b89"
Accept-Ranges: bytes
Content-Length: 12
Keep-Alive: timeout=15, max=40
Connection: Keep-Alive
Content-Type: application/download-me
----------------------------------------------------------

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I have solved partialy the problem. now with this in .htaccess :

<FilesMatch "\.(?i:txt)$">
  ForceType application/octet-stream
  Header set Content-Disposition attachment
</FilesMatch>

Opera and IE display prompt for download file, BUT chrome NO.

My solution work for and with all browser