The actual settings simple mode uses depend on the encoder and the output resolution. To see the "real" settings used, make a recording and open the "current log file", which will contain a log of the recording session. Help->Log Files->View current log. Go near the end of that log and search for the string "Recording Start". Above the line with that, you will see the settings actually used, like this:
16:06:54.501: [NVENC encoder: 'simple_h264_recording'] settings:
16:06:54.501: rate_control: CQP
16:06:54.501: bitrate: 0
16:06:54.501: cqp: 16
16:06:54.501: keyint: 250
16:06:54.501: preset: hq
16:06:54.501: profile: high
16:06:54.501: level: auto
16:06:54.501: width: 2560
16:06:54.501: height: 1440
16:06:54.501: 2-pass: true
16:06:54.501: b-frames: 2
16:06:54.501: GPU: 0
16:06:54.501:
16:06:54.801: warning: Using global_quality with nvenc is deprecated. Use qp instead.
16:06:54.995: ---------------------------------
16:06:54.995: [FFmpeg aac encoder: 'simple_aac_recording'] bitrate: 128, channels: 2, channel_layout: 3
16:06:54.995:
16:06:55.533: ==== Recording Start ===============================================
16:06:55.533: [ffmpeg muxer: 'simple_file_output'] Writing file 'D:/Dateien/Alex/Videos/Aufzeichnungen/2019-02-02 16-06-54.mkv'...
Don't take my settings above, look into your own log instead, because that will most certainly look different!