Highlighting a Cell prompts a box to appear, Not a comment box, I'd like to edit it

[c.goan]

As said a box appears with information guiding the user to what should be entered.

I inherited this spreadsheet and would like to edit the contents of this box and also learn how to make them myself.

Thanks

Edit:
Also I'd like to note that the box does not respond to right clicking

[Jakobshavn]

There are two types of pop-up boxes:

1. Data Validation pop-ups - visible on click
2. Comment Pop-ups - visible on mouse-over

Yours is probably Data Validation.

1. Click on the cell
2. Data tab > Data Validation > Input Message tab - then edit the message

[c.goan]

Thank you

Worked prefectly