Here’s what I do:
The EDITOR only edits or enters chords in a chart in the default (concert) key which is usually set on the info (i) screen of the editor when the chart is first written. The default key can be reset later (“hard” transposition).
Write / make / enter / edit the chart using the chord sequence
in the concert key.
Now you have a chart in concert key.
With the player controls visible, (tap on the chart if necessary) select the key button on the right side of the chart beside the tempo and player repeats selections.
You can use this Transposition screen to adjust the song’s concert key (“soft” transposition) this is NOT used to alter the key for use with horns etc.
On the right side of TRANSPOSITION is a trumpet

tap it.
On the Transposing instrument screen
Select your instrument.
THIS IS A GLOBAL SETTING. EVERY CHART IN YOUR LIBRARY WILL BE TRANSPOSED FROM CONCERT KEY TO MATCH YOUR INSTRUMENT’S TRANSPOSED KEY.
THE PLAYER WILL STILL PLAY THE CHART IN THE CONCERT KEY
(or in the “soft” transposed concert key which will also adjust the displayed key for your instrument,)
Here’s how you can tell that a chart is displayed for a transposed instrument:
Top-left on the chart is the style suggestion eg. (Medium Swing) if that’s all you see, it’s a concert-key chart. If the chart is displayed for a transposed instrument.
You will see the style and (key)-part eg. (Medium Swing) Eb-part or Bb-part etc.
If you are copying a chart from a “Eb Book” or “Bb Book” instead of a C-Concert Book, you can enter the transposed chords directly in the Editor, then on the info screen change the default chart to the appropriate concert key using
“Set AND transpose” (not just SET).
When you share charts in the Forums, please set Transposing Instrument to C so your shared charts in the will be displayed in concert key.
Thanks

)BOB
More:
Read this
https://forums.irealpro.com/threads/Transposing-for-Eb-Sax.7710/
And this
https://technimo.helpshift.com/a/ireal-pro/?s=transposition&f=transposing-instrument&l=en