how to change text in slide layer

What you are trying to edit may be an image.  If it is (look at the timeline) just create a new image and replace it for the old one. 

Or it may be a shape.  If it is a shape, see if you can edit the states for the shape.

Hello thanks for the answer but as said before if you look at the image you see that the text is underlined with a red wavy line so the program considers it to be text I presume. if I modify the shape the background of the image moves and if I change the background to white color the text disappears because it is also white but the red lines remain

for me it looks like a grouped image with text but I do not have the possibility to separate the text from the illumination the option is grayed out

and another thing who look like me Strange if I make tight clic on the picture copy it and paste it in GIMP for example I have only the background text and logo disapear as if they are separate.

Hello Jean,

If you select that box, and look at the timeline, is there a little arrow to the left of the eye? If so, then that is a grouping of things, and if you click the arrow, it should ungroup, and one of the things should be the text object, which you should then be able to edit. Usually when people group objects together, Storyline automatically calls it Group 1, 2, 3, etc., but it could have been renamed.

Here you can see I have that shape selected, and it is highlighted in the Timeline menu.

If you click the arrow to expand the group, you should be able to select and edit the individual components in the group.

thank you but I have no arrow. So I make new pictures 

I just make two pictures perhaps the solution could be found in this pictures

And the second when I change the background in white . you can see the red underlines

I don't know enough about this software to find the solution. for the moment so I redo the images with the text which this time will be integrated into the image. Thank you for your help I will come back to the next problem which with my low  level will not be long in coming.

thank you both 

I appreciate the additional details, Jean Marc.

I'm curious if the shapes have been edited using the States tab since you do not have grouped objects or are the base layer objects displaying through the layer?

Storyline 360: Adding and Editing States

I'd be happy to take a look at your project file to investigate what's happening with your permission. You can share it publicly here or send it to me privately by uploading it here. I'll delete it when troubleshooting is complete.

Hello
sorry for the delay I sent you a part of this file because it's weight is 70 Mo and I am not sure that you need all the file.
I remenber you I am beginner and I have to update this file and it's not me who make it in the first time.I thought I had removed the slides but I only removed the inside. the slide concerned is the last of Chapter 1

I tried to send you with your link but never found where to send it I try all button but never have confirmation starting.
thank you
salutations
Jean Marc Laumond

Hi Jean Marc,

Thanks for sharing the .story file so that I could take a look. It's just as I thought. The objects were added to the States Tab:

Storyline 360: Adding and Editing States

Thank you for your answer I would never have thought that it was necessary to go to this menu to be able to correct the text

Leslie this is so helpful thank you!!! :-)