Diego Iglesias

Ok finally I was able to fix it. I started to playing around with the view tag, and I pressed dock tools and seems to work fine, nevertheless. tank you very much for your help, I apologize, I'm just a beginner!!!
Many thanks to you!!!

Welcome to the Affinity Forums @Diego Iglesias  
Can you please provide a screenshot of your Affinity app, or a screen recording showing the options you cannot select currently?
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Many thanks in advance!

Hi Diego!
There are some features in the toolbar that are small menus with tools inside (they have a small triangle in the right bottom corner). If you click on them, you open a small menu with some tools. But you have to click on one tool in this menu to select it. Only opening the menu will not select a tool. - If this might be your problem.
And, of course, without a document opened, you can't select a tool. They are all greyed out in that case.
And a third opportunity: if you have the "Customise Tools" panel open, you can't select tools. Close this panel first. It is only made to configure your toolbar.
Just to exclude this error sources.

That's what I meant with the third point: seems like you opened the "Customize Tools" panel (from the "View" menu). In that case you can drag and drop tools to configure the tool bar (add some more tools, remove some and/or change their order). But you can't activate tools to work with it as long as this panel is opened. For this you have to close the "Customize Tools" panel first.