Saving changes made in excel

[jjjtrio]

I have a list of names and numbers in text format. I open or upload the file
in excel to filter out by area code. I need this new list to be saved in csv
or plain text doc. When I try to save the new list in one of these formats, I
loose what I have filtered out it is the same as the original file.

The only way I found to save the changes I'v made is to save as excel
workbook, but it is .xlxs format which i can't use.

Thanks in advance
Jarodd

 

[jjjtrio]

I need to keep the data base to use for future lists. should I try to use
access?