Is it can or how to downgrade the AutoCad to my working versions, such as  from new Version 2022 to old versions 2000 ~ 2018?

You do a "save as" and choose the appropriate version or you go to OPTION / Option and save and set definitively the version so that each time you do as simple save it will go to the choosen version.I personally don't do the second option as I had already have bad things on files such as a fatal error when simply trying to open some modified files.

In fact if I remember well, the 2022 is in fact a 2018 anyway when saved, you should check in OPTIONS / Options and save.
philippe JOSEPH2022-06-03 21:06:40

I am sorry that I take a wrong questions. Now my using AutoCad version of 2017 & 2018. May AutoCad files are 2019 to 2022 or 23. How to or can its downgrade these files to 2017 or 2018 or 2000 formats. thank you very much.

It's the same : try and do a "saveas" and choose the 2000 version.
Then to verify if it's OK open the downgraded file on a computer with only AutoCAD 2000 or :Open it on your AutoCAD 2022, type F2 to read better the command line and it should be indicated : Opening of an AutoCAD 2000 file.If it hasn't been downgraded correctly you should not be abble to open it with an AutoCAD 2000.
philippe JOSEPH2022-06-04 13:02:15

FILE / SAVE AS :

[QUOTE=tmwong9797]I am sorry that I take a wrong questions. Now my using AutoCad version of 2017 & 2018. May AutoCad files are 2019 to 2022 or 23. How to or can its downgrade these files to 2017 or 2018 or 2000 formats. thank you very much.[/QUOTE]
Open the drawings in DWG TrueView and do a "Save as" to the version of AutoCAD you are working in.  

any free software autocad ?

If you mean for converting newer-version files to older versions, DWG TrueView is free, and can do that.  See >here<.

[QUOTE=rizal1]any free software autocad ?[/QUOTE]
Are you looking for 2D, 3D or both?

Dear anybody, and thank you very much. I have downloaded the TrueView 2023 and solved the problems.