Exporting .xlf files with all original trans-unit id attributes?

Greetings all,

I'm using SDL Trados Studio 2021.

I am trying to understand how to create a project beginning with importing our original .xlf translation file, editing and adding translations and then exporting the translation file to its original .xlf utf-8 format, while maintaining its original and essential trans-unit id attributes.

The problem we are encountering is that the exported SDL Trados files do not retain the potential trans-unit id attributes: resAttributeName, resIdentifier, resIdentifierType, resname, and restype in our source .xlf translation files.

Example:
BEFORE

xlf, utf-8 encoded
<trans-unit id="xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" resAttributeName="DisplayName" resname="Usage_User" restype="subject"><source>User</source><target>Utilisateur</target><note>A person who has access to the application.</note></trans-unit>

AFTER (export from SDL Trados)
The file output is in .sdlxliff, utf-8-bom format
<trans-unit id="xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"><source>source text</source><seg-source><mrk mtype="seg" mid="995">added text</mrk></seg-source><target><mrk mtype="seg" mid="995">target text</mrk></target><sdl:seg-defs><sdl:seg id="995" conf="Draft"><sdl:value key="SegmentIdentityHash">Bwru/0EmJi96m4n9qljUA7dYY+Q=</sdl:value><sdl:value key="created_by">text</sdl:value><sdl:value key="created_on">02/24/2021 09:56:13</sdl:value><sdl:value key="last_modified_by">text</sdl:value><sdl:value key="modified_on">02/24/2021 09:56:13</sdl:value></sdl:seg></sdl:seg-defs><sdl:cmt id="xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"/></trans-unit>

The SDL Trados Studio output files also contain a lot of other undesired content such as a BASE-64 copy of the original file.

Can someone help me understand what configurations and/or proper workflow is needed to ensure that the edited translation file is saved without losing the trans-unit id attributes and in the same file format and encoding as the original.

Thank you :)