Hi! I wolud like to open txt , lst and csv files in browser mode, without owncloud apps for preview. How can i do this?
In case what @cs35 suggested is not what you wanted:
What do you mean with browser mode and owncloud apps for preview? Perhaps you can post some screenshots of the current behavior and then explain what you want to achieve.
Your desired behavior is not possible without an app.
There is the app https://marketplace.owncloud.com/apps/files_texteditor which looks close to your requirements.
.txt and .lst files are opened by default. .csv might work out of the box but it might be possible, you would have to add a text mime type as described in https://doc.owncloud.com/server/admin_manual/configuration/mimetypes/