Mona,
I don't know what specific video that pka4916 is talking about but I ran a test on a randomly selected Tubi video. The selection pop-up left a lot to be desired with only allowing the selection of the resolution and bitrate. See below.
So, in that respect there is no way to select a sub (other than what is preset in the Settings.) I did the download as shown and had no problem. Listening to the playback I had to actually turn down the volume. It definitely did NOT sound in mono. When I looked at the MediaInfo report I was not surprised to see it was in Stereo because that is my preset. I just don't have the physical room required for a multichannel audio system to sound the way it should. What did surprise me was that there was built into the MKV a subtitle listed as "unknown." My preset for subtitles is "None" since I am an English speaker. When the "unknown" subtitle was turned on on my player, it turned out to be an English (CC).
General
Unique ID : 295450163921782365772915349913874021139 (0xDE45A1BC25005FE8BA34DAF407553B13)
Complete name : R:\AFAB_Out\Tubi\Coyote Ugly.mkv
Format : Matroska
Format version : Version 4
File size : 1.38 GiB
Duration : 1 h 40 min
Overall bit rate : 1 957 kb/s
Movie name : Coyote Ugly
Encoded date : UTC 2022-09-08 00:16:27
Writing application : mkvmerge v68.0.0 ('The Curtain') 64-bit
Writing library : libebml v1.4.2 + libmatroska v1.6.4
Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : A_AAC-2
Duration : 1 h 40 min
Bit rate : 126 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 kHz
Frame rate : 43.066 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 90.5 MiB (6%)
Default : Yes
Forced : No
Text
ID : 3
Format : UTF-8
Codec ID : S_TEXT/UTF8
Codec ID/Info : UTF-8 Plain Text
Duration : 1 h 38 min
Bit rate : 82 b/s
Frame rate : 0.336 FPS
Count of elements : 1988
Stream size : 59.8 KiB (0%)
Default : No
Forced : No
Comment