What tool to edit subtitles embeded in mp4 video?

$ ffmpeg -i myvideo.mp4
ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple clang version 13.1.6 (clang-1316.0.21.2.5)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/5.0.1_3 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox
  libavutil      57. 17.100 / 57. 17.100
  libavcodec     59. 18.100 / 59. 18.100
  libavformat    59. 16.100 / 59. 16.100
  libavdevice    59.  4.100 / 59.  4.100
  libavfilter     8. 24.100 /  8. 24.100
  libswscale      6.  4.100 /  6.  4.100
  libswresample   4.  3.100 /  4.  3.100
  libpostproc    56.  3.100 / 56.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'myvideo.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: mp42iso2avc1mp41
    creation_time   : 2022-08-03T21:58:07.000000Z
    encoder         : HandBrake 1.5.1 2022011000
  Duration: 00:11:05.40, start: 0.000000, bitrate: 1635 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, smpte170m/bt470bg/bt470bg, progressive), 712x576 [SAR 16:15 DAR 178:135], 1454 kb/s, 25 fps, 25 tbr, 90k tbn (default)
    Metadata:
      creation_time   : 2022-08-03T21:58:07.000000Z
      handler_name    : VideoHandler
      vendor_id       : 
  Stream #0:1[0x2](bre): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 162 kb/s (default)
    Metadata:
      creation_time   : 2022-08-03T21:58:07.000000Z
      handler_name    : Stereo
      vendor_id       : 
  Stream #0:2[0x3](bre): Subtitle: dvd_subtitle (mp4s / 0x7334706D), 720x576, 6 kb/s (default)
    Metadata:
      creation_time   : 2022-08-03T21:58:07.000000Z
      handler_name    : Brezhoneg
  Stream #0:3[0x4](fra): Subtitle: dvd_subtitle (mp4s / 0x7334706D), 720x576, 6 kb/s
    Metadata:
      creation_time   : 2022-08-03T21:58:07.000000Z
      handler_name    : Français
At least one output file must be specified