alternate guitar tunings

see: https://musescore.org/en/handbook/tablature#edit-string-data

To edit the strings on your score,

right click the guitar staff
select staff properties
click Edit string data near the bottom of the window
click the string you want to edit - DO NOT CHECK THE BOX*
click edit string...
click the string then OK
click OK again
click OK again
Open the staff properties again
click the edit pencil next to E2 on the amateur pitch and select the D2,
do the same on the professional pitch side. This prevents notes under E2 from being displayed in red.
Click OK

*Checking the box indicates this is an open string and the string will have no frets assigned to it.