Currently I'm using target keywords in the menu: keyword + my service, but if i change it to my service (don't include keyword) with this situation, does it affect to my ranking for target keywords and my home page? thanks
If I understand your question correctly, your current navigation menu links contain your keyword and you're asking whether removing the keywords from the links will affect your ranking for those keywords? The short answer is: YES, it will. The long answer is: it depends. If your site is new and/or has weak link profile (i.e. your rankings rely mostly on your on-page optimization and internal linking structure), you are likely to see drop in SERPs for your desired keywords if you remove them from your internal links. If, however, your site has high authority and a very strong link profile, the effect on SERPs could be very small, even unnoticeable.
The word "Keyword" by itself is a keyword. If your targeted keyword is not the word "Keyword" and its only "my service" then it doesn't matter in any ways.
A Navigation Menu in SEO can play a huge role in optimizing your website for search engines. The reason being is when a search engine crawls your website, it is going to read everything in the header and the first 100 or so keywords in your body which would usually be your article..
Yes you should use your keywords in sub menu that are related to the pages. dont stuff keywords in submenu in order to rank in SE..
Yes it will effect ranking of your inner pages. using keyword in navigathion is good to optimize your internal pages for search engine.